Systems, methods and apparatuses for formation and insertion of tissue prosthesis

ABSTRACT

A tissue prosthesis insertion system includes a first assembly comprising a plurality of nested tubes, one of the tubes being a carrier tube which, in use, receives a component of a tissue prosthesis at a distal end of the carrier tube. A magnetic mount is carried at a proximal end of the first assembly. A second assembly is removably attachable to the first assembly. An attachment device is carried at a distal end of the second assembly, the attachment device being responsive to the magnetic mount of the first assembly, the magnetic mount and the attachment device carrying complementary engaging formations to facilitate hermetic sealing between the magnetic mount and the attachment device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.60/915,410, filed on May 1, 2007.

Additionally, each of the following applications are herein incorporatedby reference, in its entirety:

-   International Application No. PCT/AU2003/001289, filed on Sep. 30,    2003;-   Australian Provisional Application No. 2002951762, filed on Oct. 1,    2002;-   International Application No. PCT/AU2006/000267, filed on Mar. 1,    2006;-   Australian Provisional Application No. 2005900952, filed on Mar. 1,    2005;-   International Application No. PCT/AU2006/001176, filed on Aug. 15,    2006;-   U.S. Provisional Application No. 60/708,687, filed on Aug. 15, 2005;-   International Application No. PCT/AU2007/00001601 filed on Oct. 22,    2007;-   U.S. Provisional Application No. 60/867,574, filed on Nov. 28, 2006;-   International Application No. PCT/AU2007/001657, filed on Oct. 31,    2007;-   U.S. Provisional Application No. 60/915,410, filed on May 1, 2007;    and-   U.S. Provisional Application No. 60/971,633 filed on Sep. 12, 2007.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to tissue prostheses and moreparticularly, the present disclosure relates to systems, methods, andapparatuses for formation and insertion of tissue prostheses.

BACKGROUND INFORMATION

Joints of the musculoskeletal system of the human or animal body rely onthe presence of healthy cartilaginous tissue for proper operation.Cartilaginous tissue can degenerate due to a number of causes, e.g., ageor injury. Degradation of the tissue can reach a point where movementcan cause severe discomfort and pain.

Degradation of tissue can occur in the spinal column. The spinal columncomprises a series of 26 mobile vertebral bones, or vertebrae, connectedby 75 stable articulations that control motion. The vertebrae aregenerally divided into posterior and anterior elements by thick pillowsof bone called pedicles. The anterior element of the vertebra is akidney shaped prism of bone with a concavity directed posteriorly andhas flat superior and inferior surfaces called end plates. Anintervertebral disc is sandwiched between adjacent pairs of vertebraeforming a joint between the adjacent pair of vertebrae. These discs areviscoelastic structures comprising a layer of strong, deformable, softtissue. The intervertebral discs are subjected to a considerable varietyof forces and moments resulting from the movements and loads of thespinal column. Each intervertebral disc has two components, being theannulus fibrosis surrounding a nucleus pulposus. The intervertebral disccooperates with end plates of the vertebrae between which it issandwiched.

The primary function of the nucleus pulposus of the disc is to give thedisc its elasticity and compressibility characteristics to assist insustaining and transmitting weight. The annulus fibrosis contains andlimits the expansion of the nucleus pulposus during compression and alsoholds together successive vertebrae, resisting tension and torsion inthe spine. The end plates of the vertebrae are responsible for theinflux of nutrients into the disc and the efflux of waste products fromwithin the disc.

With age or injury, a degenerative process of the disc may occur wherebyits structures undergo morphological and biological changes affectingthe efficiency with which the disc operates. Thus, the nucleus pulposusmay reduce in volume and dehydrate resulting in a load reduction on thenucleus pulposus, a loss in intradiscal pressure and, hence, additionalloading on the annulus fibrosis. In a normally functioning disc, theintradiscal pressure generated results in deformation of the end platesof the adjacent vertebrae generating the natural pumping action whichassists in the influx of the nutrients and the efflux of waste productsas stated above. A drop in intradiscal pressure therefore results inless end plate deformation. The nutrients supplied to the discal tissueare reduced and metabolic wastes are not removed with the sameefficiency. This contributes to a degenerative cascade.

Radial and circumferential tears, cracks and fissures may begin toappear within the annulus fibrosis. If these defects do not heal, someof the nuclear material may begin to migrate into the defects in theannulus fibrosis. Migration of the nuclear material into the annulusfibrosis may cause stretching and delamination of layers of the annulusfibrosis resulting in back pain due to stimulation of the sinu-vertebralnerve. An intervertebral disc without a competent nucleus is unable tofunction properly. Further, since the spine is a cooperative system ofelements, altering the structure and mechanics at one location of thespinal column may significantly increase stresses experienced atadjacent locations thereby further contributing to the degenerativecascade.

In the past, operative intervention has occurred to relieve lower backpain arising from intervertebral disc degeneration. Most of thisoperative intervention has been by way of a discectomy where leakingnuclear material is removed or, alternatively, fusion. The primarypurpose of a discectomy is to excise any disc material that is impingingon the spinal nerve causing pain or sensory changes. Fusion meanseliminating a motion segment between two vertebrae by use of a bonegraft and sometimes internal fixation. Biomechanical studies show thatfusion alters the biomechanics of the spine and causes increasedstresses to be experienced at the junction between the fused and unfusedsegments. This promotes degeneration and begins the degenerative cycleanew. Clearly, being an invasive operative procedure, fusion is a riskyprocedure with no guarantee of success.

Due to the minimal success rate of these previous procedures, as well astheir inability to restore complete function to the spinal column,alternative treatments have been sought in the form of artificial discreplacements. Theoretical advantages of artificial disc replacement overa fusion procedure include preservation or restoration of segmentalmotion in the spine, restoration of intervertebral architecture andforaminal height, sparing of adjacent segments of the spine fromabnormal stresses and restoration of normal biomechanics across thelumbar spine. The established artificial disc replacement procedureconsists of techniques that require a surgical incision on the abdomen,retraction of large blood vessels, a total excision of the anteriorlongitudinal ligament, anterior and posterior annulus along with thenucleus and near total removal of the lateral annulus and implantationof an articulated prosthesis. This is a major spinal columnreconstruction operation carried out by a very invasive technique.

Accordingly, the present inventors have observed that there is a needfor surgical procedures, methods, and/or systems which, as far aspossible, restore the biomechanics of joints such as those betweenadjacent vertebrae of the spine by the provision of a tissue prosthesismimicking natural, healthy cartilaginous tissue as well as a means ofcarrying out the surgical procedure in a minimally invasive mannerand/or percutaneous manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-8 show schematic illustrations of various steps of a method, inaccordance with certain exemplary embodiments disclosed herein, forforming a tissue prosthesis in situ at a site in a patient's body;

FIG. 9 shows a schematic illustration of a delivery device for use inaccordance with certain exemplary embodiments disclosed herein;

FIG. 10 shows a schematic, sectional side view of part of equipment, inaccordance with certain exemplary embodiments disclosed herein, forforming a tissue prosthesis, in situ at a site in a patient's body;

FIG. 11 shows a schematic, sectional side view of the equipment inaccordance with certain exemplary embodiments disclosed herein;

FIG. 12 shows a schematic, side view and end view of part of theequipment in accordance with certain exemplary embodiments disclosedherein:

FIG. 13 shows a sectional side view of an envelope, attached to adelivery device, the envelope forming part of a tissue prosthesis, inaccordance with certain exemplary embodiments disclosed herein;

FIG. 14 shows a sectional side view of another mounting of the envelopeon the delivery device in accordance with certain exemplary embodimentsdisclosed herein;

FIGS. 15-17 show different shapes of envelopes for use in the tissueprosthesis in accordance with certain exemplary embodiments disclosedherein;

FIG. 18 shows a plan view of another embodiment of equipment for forminga tissue prosthesis, in situ, at a site in a patient's body inaccordance with certain exemplary embodiments disclosed herein;

FIG. 19 shows a sectional side view taken along line 19-19 in FIG. 18 inaccordance with certain exemplary embodiments disclosed herein;

FIG. 20 shows, on an enlarged scale, a sectional side view of the partof the equipment encircled by circle “20” in FIG. 19 in accordance withcertain exemplary embodiments disclosed herein;

FIG. 21 shows, on an enlarged scale, a sectional side view of the partof the equipment encircled by circle “21” in FIG. 19 in accordance withcertain exemplary embodiments disclosed herein;

FIG. 22 shows a sectional side view of yet a further embodiment ofequipment for forming a tissue prosthesis, in situ, at a site in apatient's body in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 23 shows on an enlarged scale, a sectional side view of the part ofthe equipment encircled by circle “23” in FIG. 22 in accordance withcertain exemplary embodiments disclosed herein;

FIG. 24 shows on an enlarged scale, a sectional side view of the part ofthe equipment encircled by circle “24” in FIG. 22 in accordance withcertain exemplary embodiments disclosed herein;

FIG. 25 shows a plan view of a first assembly of a tissue prosthesisinsertion system in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 26 shows a sectional side view of the first assembly of the systemof FIG. 25 taken along line 26-26 in FIG. 25 in accordance with certainexemplary embodiments disclosed herein;

FIG. 27 shows a sectional side view, on an enlarged scale, of the partof the first assembly surrounded by circle “27” in FIG. 26 in accordancewith certain exemplary embodiments disclosed herein;

FIG. 28 shows a sectional side view, on an enlarged scale, of the partof the first assembly surrounded by circle “28” in FIG. 26 in accordancewith certain exemplary embodiments disclosed herein;

FIG. 29 shows a plan view of an assembly of the tissue prosthesisinsertion system in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 30 shows a sectional side view of the assembly of the system takenalong line 30-30 in FIG. 29 in accordance with certain exemplaryembodiments disclosed herein;

FIG. 31 shows a sectional side view, on an enlarged scale, of the partof the assembly surrounded by circle “31” in FIG. 30 in accordance withcertain exemplary embodiments disclosed herein;

FIG. 32 shows a sectional side view, on an enlarged scale, of the partof the assembly surrounded by circle “32” in FIG. 30 in accordance withcertain exemplary embodiments disclosed herein;

FIG. 33 shows a plan view of a valve member forming part of a tissueprosthesis of the system in accordance with certain exemplaryembodiments disclosed herein;

FIG. 34 shows an end view of the valve member in accordance with certainexemplary embodiments disclosed herein;

FIG. 35 shows a sectional side view of the valve member taken along line35-35 in FIG. 34 in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 36 shows a schematic side view of a working cannula of the assemblyin position after formation of the tissue prosthesis in accordance withcertain exemplary embodiments disclosed herein;

FIG. 37 shows a schematic side view of a further part of the systeminserted into the cannula to complete formation of the tissue prosthesisin accordance with certain exemplary embodiments disclosed herein;

FIGS. 38A and B shows a sectional side view of a prosthesis deliverysystem in accordance with certain exemplary embodiments disclosedherein:

FIG. 39 shows, on an enlarged scale, a sectional side view of theencircled portion of the system marked “39” in FIGS. 38A and 388 of thedrawings in accordance with certain exemplary embodiments disclosedherein;

FIG. 40 shows a component of a prosthesis delivery system in accordancewith certain exemplary embodiments disclosed herein;

FIG. 41 shows a sectional side view of a part a prosthesis deliverysystem including the component of FIG. 40 in accordance with certainexemplary embodiments disclosed herein:

FIG. 42 shows a sectional side view of a part of a further embodiment ofa prosthesis delivery system including the component of FIG. 40 inaccordance with certain exemplary embodiments disclosed herein:

FIGS. 43a, 43b and 43c show, respectively, front, side and plan views ofan intervertebral disc implant, in accordance with certain exemplaryembodiments disclosed herein;

FIGS. 44a, 44b and 44c show, respectively, front, side and plan views ofan intervertebral disc implant, in accordance with certain exemplaryembodiments disclosed herein:

FIGS. 45a, 45b and 45c show, respectively, front, side and plan views ofan intervertebral disc implant, in accordance with certain exemplaryembodiments disclosed herein;

FIGS. 46a, 46b and 46c show, respectively, front, side and plan views ofan intervertebral disc implant, in accordance with certain exemplaryembodiments disclosed herein:

FIGS. 47a, 47b and 47c show, respectively, front, side and plan views ofan intervertebral disc implant, in accordance with certain exemplaryembodiments disclosed herein;

FIGS. 48a, 48b and 48c show, respectively, front, side and plan views ofan intervertebral disc implant, in accordance with certain exemplaryembodiments disclosed herein;

FIGS. 49a, 49b and 49c show, respectively, front, side and plan views ofan intervertebral disc implant, in accordance with certain exemplaryembodiments disclosed herein;

FIGS. 50a, 50b and 50c show, respectively, front, side and plan views ofan intervertebral disc implant, in accordance with certain exemplaryembodiments disclosed herein:

FIGS. 51a, 51b and 51c show, respectively, front, side and plan views ofan intervertebral disc implant, in accordance with certain exemplaryembodiments disclosed herein;

FIGS. 52a, 52b and 52c show, respectively, front, side and plan views ofan intervertebral disc implant, in accordance with certain exemplaryembodiments disclosed herein;

FIGS. 53a, 53b and 53c show, respectively, front, side and plan views ofan intervertebral disc implant, in accordance with certain exemplaryembodiments disclosed herein;

FIG. 54 shows a schematic side view of an intervertebral disc implant ina first configuration, in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 55 shows a schematic plan view of the implant of FIG. 54 in asecond configuration in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 56 shows a schematic side view of an intervertebral disc implant ina first configuration, in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 57 shows a schematic plan view of the implant of FIG. 56 in asecond configuration in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 58 shows a schematic side view of an intervertebral disc implant ina first configuration, in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 59 shows a schematic plan view of the implant of FIG. 58, in use,in a second configuration in accordance with certain exemplaryembodiments disclosed herein;

FIG. 60 shows a schematic plan view of an intervertebral disc implant,in accordance with certain exemplary embodiments disclosed herein:

FIG. 61 shows a schematic plan view of an intervertebral disc implant,in accordance with certain exemplary embodiments of the inventionsdisclosed herein;

FIG. 62 shows a schematic three dimensional view of the implant of FIG.61 in accordance with certain exemplary embodiments disclosed herein;

FIG. 63 shows a schematic three dimensional view of an intervertebraldisc implant, in accordance with certain exemplary embodiments disclosedherein;

FIG. 64 shows a schematic three dimensional view of an intervertebraldisc implant, in accordance with certain exemplary embodiments disclosedherein;

FIG. 65 shows a three dimensional view of an intervertebral discimplant, in accordance with certain exemplary embodiments disclosedherein;

FIG. 66 shows a sectional side view of the implant of FIG. 65 inaccordance with certain exemplary embodiments disclosed herein;

FIG. 67 shows a three dimensional view of the implant of FIG. 65, inaccordance with certain exemplary embodiments disclosed herein;

FIG. 68 shows a schematic three dimensional view of an intervertebraldisc implant, in accordance with certain exemplary embodiments disclosedherein;

FIG. 69 shows a schematic, sectional plan view of an intervertebral discimplant, in accordance with certain exemplary embodiments disclosedherein:

FIG. 70 shows sectional end view taken along line 70-70 in FIG. 69 inaccordance with certain exemplary embodiments disclosed herein;

FIG. 71 shows a schematic, sectional three dimensional view of anintervertebral disc implant, in accordance with certain exemplaryembodiments disclosed herein;

FIG. 72 shows embodiments disclosed herein; on an enlarged scale, thedetail encircled by “72” in FIG. 71 in accordance with certain exemplary

FIG. 73 shows the detail of FIG. 72 in a collapsed configuration inaccordance with certain exemplary embodiments disclosed herein:

FIG. 74 shows a three dimensional view of a system, in accordance withcertain exemplary embodiments disclosed herein, for implanting anintervertebral disc implant;

FIG. 75 shows, on an enlarged scale, a three dimensional view of thesystem of FIG. 74 in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 76 shows a schematic, sectional side view of an introducer for asystem, in accordance with certain exemplary embodiments disclosedherein, for implanting an intervertebral disc implant.

FIGS. 77-79 illustrate, schematically, various stages of the use of anembodiment of equipment, in accordance with certain exemplaryembodiments disclosed herein, for preparing a site for the implantationof a tissue prosthesis;

FIGS. 80-85 illustrate, schematically, various stages of the use ofanother exemplary embodiment of equipment, in accordance with certainexemplary embodiments disclosed herein, for preparing a site for theimplantation of a tissue prosthesis;

FIG. 86 illustrates spinal disk load vs. displacement as determined inaccordance with a finite element analysis of an exemplary implant:

FIG. 87 illustrates a sectional view of a ball valve inside an envelopein an open position in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 88 illustrates a sectional view of a ball valve inside an envelopein a closed position in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 89 illustrates a sectional view of a umbrella valve inside anenvelope in an open position in accordance with certain exemplaryembodiments disclosed herein:

FIG. 90 illustrates a sectional view of a umbrella valve inside anenvelope in a closed position in accordance with certain exemplaryembodiments disclosed herein;

FIG. 91 illustrates an exemplary valve-like configuration where thediameter gradually decreases to limit backflow in accordance withcertain exemplary embodiments disclosed herein;

FIG. 92 illustrates a means of sealing through an O-ring (the crosssection of the O-ring can be seen in the close up view) in accordancewith certain exemplary embodiments disclosed herein;

FIG. 93 illustrates a means of sealing through a luer lock in accordancewith certain exemplary embodiments disclosed herein:

FIG. 94 illustrates a means of sealing through a luer slip or luerfitting (taper fit) in accordance with certain exemplary embodimentsdisclosed herein;

FIG. 95 illustrates an exemplary priming means in which air is ventedthrough a slit as the biomaterial primes the tube in accordance withcertain exemplary embodiments disclosed herein;

FIG. 96 illustrates a single lumen delivery means where the air ventsaround the space between the filler tube and the valve-like structure inaccordance with certain exemplary embodiments disclosed herein; and

FIG. 97 illustrates an end on view of the space around the tube when ithas been pushed into the valve in accordance with certain exemplaryembodiments disclosed herein.

DETAILED DESCRIPTION

In certain exemplary embodiments disclosed herein, there may be providedmethods of forming a tissue prosthesis in situ at a site in a patient'sbody, that comprise accessing the site in the patients body; ifnecessary, removing tissue from the site to form a cavity; inserting anenvelope of a biologically inert, elastically deformable material intothe cavity; charging a filler material, in a fluent state, into theenvelope to cause the envelope to expand and, if necessary, stretch andconform to the shape of the cavity, and allowing the filler material tocure, the filler material being of the same class of material as theenvelope so that, when the filler material has cured, a unifiedprosthesis is formed. In some aspects, these methods may be carried outusing minimally invasive techniques. In some aspects, these methods maybe carried out using percutaneous techniques. In some aspects, thesemethods may be carried out using a combination of minimally invasive andpercutaneous techniques.

In certain exemplary embodiments disclosed herein, there may be providedmethods of forming a tissue prosthesis in situ at a site in a patient'sbody, that comprise means for accessing the site in the patient's body;if necessary, means for removing tissue from the site to form a cavity;means for inserting an envelope of a biologically inert, elasticallydeformable material into the cavity; means for charging a fillermaterial, in a fluent state, into the envelope to cause the envelope toexpand and or stretch, if necessary and conform to the shape of thecavity; and means for allowing the filler material to cure, the fillermaterial being of the same class of material as the envelope so that,when the filler material has cured, a unified prosthesis is formed. Insome aspects, these methods may be carried out using minimally invasivetechniques. In some aspects, these methods may be carried out usingpercutaneous techniques. In some aspects, these methods may be carriedout using a combination of minimally invasive and percutaneoustechniques.

In certain exemplary embodiments disclosed herein, the methods mayinclude accessing the site percutaneously in a surgical procedure thatis less invasive than conventional procedures. Hence, the method may beused to perform less invasive intervertebral disc nucleus replacementand the method may comprise forming an aperture in an annulus fibrosisof the disc percutaneously; extracting a nucleus pulposus of the disc toform a disc cavity bounded by the annulus fibrosis of the disc and endplates of vertebrae between which the disc is located; inserting theenvelope, in a first state, into the cavity through the aperture;charging the filler material into the envelope to cause the envelope toexpand and conform to the shape of the disc cavity; allowing the fillermaterial to cure to form, together with the envelope, the substantiallyunified prosthesis; and occluding the aperture.

In certain exemplary embodiments disclosed herein, there may be providedmethods of preparing a first assembly of a tissue prosthesis system forinsertion into a patient's body, the methods comprising providing afirst assembly which comprises a plurality of nested tubes, one of thetubes being a carrier tube; mounting a component of the prosthesis on adistal end of the carrier tube, the component being of an elasticallydeformable material; inserting a stiffening member into the firstassembly so that the stiffening member extends into an interior of thecomponent and causing a proximal end of the stiffening member to engagea proximal end of the first assembly; attaching a withdrawing device tothe first assembly so that the withdrawing device is in fluidcommunication, at least with the interior of the component; andoperating the withdrawing device to reduce the pressure, at least in theinterior of the component to cause the component to collapse about thestiffening member.

In certain embodiments disclosed herein, there may be provided methodsof preparing a first assembly of a tissue prosthesis system forinsertion into a patient's body, the methods comprising means forproviding a first assembly which comprises a plurality of nested tubes,one of the tubes being a carrier tube; means for mounting a component ofthe prosthesis on a distal end of the carrier tube, the component beingof an elastically deformable material; means for inserting a stiffeningmember into the first assembly so that the stiffening member extendsinto an interior of the component and causing a proximal end of thestiffening member to engage a proximal end of the first assembly; meansfor attaching a withdrawing device to the first assembly so that thewithdrawing device is in fluid communication with the interior of thecomponent; and means for operating the withdrawing device to reduce thepressure in the interior of the component to cause the component tocollapse about the stiffening member.

In certain exemplary embodiments of the disclosed herein, there may beprovided methods of forming a tissue prosthesis at a site in a patient'sbody, the methods comprising providing a first assembly comprising aplurality of nested tubes, one of the tubes being a carrier tube with acomponent of the prosthesis carried at a distal end of the carrier tube;inserting the first assembly into a cannula placed in the patient'sbody, whereby the working cannula or cannula provides percutaneousaccess to the disc; engaging (e.g. magnetically attaching) a secondassembly to a proximal end of the first assembly; and charging a fillermaterial from the second assembly into the component and allowing thefiller material to set.

In certain exemplary embodiments disclosed herein, there may be providedmethods of implanting an intervertebral disc implant into anintervertebral disc, the methods comprising percutaneously performing anucleotomy on the disc to remove a at least a portion of the nucleuspulposus of the disc to create a volume, inserting an envelope of theimplant into the volume; charging an interior of the envelope withfiller material in a manner to allow the envelope to expand to conformsubstantially to the volume, and causing the interior of the envelope tobe closed off to retain the filler material within the envelope. Thefiller material may be selected to mimic, enhance or at least restore asmuch as possible the natural biomechanical characteristics of thenucleus pulposus of the disc. In certain embodiments, the fillermaterial (e.g., the implant) may cooperate with the annulus to restoreat least a portion of the natural biomechanical characteristics of thedisc.

In certain embodiments, the various methods of implanting anintervertebral disc implant described throughout the specification maybe performed in less time than prior art methods. For example, incertain embodiments, the method may be performed in less than 30minutes, or less than 20 minutes, or less than 15 minutes, or less than10 minutes. In certain embodiments, the method, excluding the chargingof the interior of the envelope, may be performed in less than 30minutes, or less than 20 minutes, or less than 15 minutes, or less than10 minutes. In certain embodiments, the method, excluding the nucleotomyprocedure may be performed in less than 30 minutes, or less than 20minutes, or less than 15 minutes, or less than 10 minutes.

In certain exemplary embodiments disclosed herein, there may be providedmethods of implanting an intervertebral disc implant into anintervertebral disc, the methods comprising means for accessing the discpercutaneously using for example a working cannula; means forpercutaneously performing a nucleotomy on the disc to remove at least aportion of the nucleus pulposus of the disc to create a volume; meansfor inserting an envelope of the implant into the volume; means forcharging an interior of the envelope with filler material in a manner toallow the envelope to expand to conform substantially to the volume; andmeans for causing the interior of the envelope to be closed off toretain the filler material within the envelope, the filler materialbeing selected to mimic natural biomechanical characteristics of thenucleus pulposus of the disc.

In certain exemplary embodiments disclosed herein, there is providedmethods of implanting an intervertebral disc implant into anintervertebral disc, the methods including a method of accessing thedisc percutaneously using for example a working cannula, a method forremoving at least a portion of the nucleus pulposus of the disc tocreate a volume; inserting at least one envelope into the volume;charging an interior of the at least one envelope with material in amanner to allow the at least one envelope to expand to substantiallyfill the volume, or partially fill the volume; and causing the interiorof the envelope to be closed off to retain the material, the fillermaterial being selected to at least partially mimic characteristics ofthe nucleus pulposus of the disc.

In certain exemplary embodiments disclosed herein, there is providedmethods of implanting an intervertebral disc implant into anintervertebral disc, the methods including means for performing anucleotomy on the disc to remove a nucleus pulposus of the disc tocreate a volume; means for inserting an envelope of the implant into thevolume; means for charging an interior of the envelope with fillermaterial in a manner to allow the envelope to expand to conformsubstantially to the volume; and means for causing the interior of theenvelope to be closed off to retain the filler material within theenvelope, the filler material being selected to mimic naturalbiomechanical characteristics of the nucleus pulposus of the disc.

In certain exemplary embodiments disclosed herein, there is providedmethods of implanting an intervertebral disc implant into anintervertebral disc, the methods including percutaneously performing anucleotomy on the disc to remove a nucleus pulposus of the disc tocreate a volume; inserting an introducer into an opening formed in anannulus of the disc; and introducing into the volume, via theintroducer, at least one element which changes from a firstconfiguration, in which the at least one element is able to be insertedinto the introducer, to a second configuration in which the at least oneelement conforms substantially to the volume.

In certain exemplary embodiments disclosed herein, devices may beprovided for forming a tissue prosthesis in situ at a site in apatient's body, the devices may comprise a delivery device displaceablyreceivable in a lumen of an introducer, the delivery device defining apassageway; an envelope carried at a distal end of the delivery device,the envelope being of a biologically inert, elastically deformablematerial capable of being expanded to conform to an interior surface ofa cavity formed at the site; and a supply of a filler materialchargeable in a fluent state into the envelope through the passageway ofthe delivery device, the filler material being of the same class ofmaterial as the envelope to form, when cured, together with theenvelope, a unified prosthesis.

In certain exemplary embodiments disclosed herein, devices may beprovided for forming a tissue prosthesis in situ at a site in apatient's body, the devices may comprise a tubular delivery device, thedelivery device defining a passageway, an envelope of the prosthesisbeing mountable to a distal end of the delivery device to be received ina cavity at the site; a filler member receivable in the passageway ofthe delivery device, the filler member being receivable with clearancein the passageway to define a gap to enable fluid to be manipulated, ordisplaced at least from the envelope; and a removal mechanism carried bythe delivery device for enabling the envelope to be removed from thedelivery device after the envelope has been charged with filler materialvia the filler member.

In certain exemplary embodiments disclosed herein, devices may beprovided for forming a tissue prosthesis in situ at a site in apatient's body, the devices may comprise a means for tubular deliverydevice, the delivery device defining a passageway, an envelope of theprosthesis being mountable to a distal end of the delivery device to bereceived in a cavity at the site; a filler member receivable in thepassageway of the delivery device, the filler member being receivablewith clearance in the passageway to define a gap to enable fluid to bemanipulated at least from the envelope; and a means for a removalmechanism carried by the delivery device for enabling the envelope to beremoved from the delivery device after the envelope has been chargedwith filler material via the filler member.

In certain exemplary embodiment disclosed herein, devices may beprovided for forming a tissue prosthesis in situ at a site in apatient's body, the devices may comprise a tubular delivery device, thedelivery device defining a passageway, an envelope of the prosthesisbeing mountable to a distal end of the delivery device to be received ina cavity at the site; a stiffening element arranged, or means forproviding a stiffening element, to project from a distal end of thedelivery device with the envelope, in use, being received over thestiffening element to be supported by the stiffening element; and aremoval mechanism carried by the delivery device for enabling theenvelope to be removed from the delivery device after the envelope hasbeen charged with filler material via the filler member.

In certain exemplary embodiment disclosed herein, tissue prosthesisinsertion systems may be provided which include a first assemblycomprising a plurality of nested tubes, one of the tubes being a carriertube which, in use, receives a component of a tissue prosthesis at adistal end of the carrier tube; a magnetic mount carried at a proximalend of the first assembly; a second assembly removably attachable to thefirst assembly; and an attachment device carried at a distal end of thesecond assembly, the attachment device being responsive to the magneticmount of the first assembly, the magnetic mount and the attachmentdevice carrying complementary engaging formations to facilitate sealingbetween the magnetic mount and the attachment device. In certainembodiments, the second assembly may have the magnetic mount where thefirst assembly has the engaging member which is sealingly responsive tothe magnetic mount of the second assembly.

In certain exemplary embodiment disclosed herein, tissue prosthesisinsertion systems may be provided which include an assembly comprising aplurality of nested tubes, one of which is a carrier tube for carrying acomponent of a tissue prosthesis at its distal end and another of whichis a filler tube received with clearance in the carrier tube to define apassage between the filler tube and the carrier tube, the proximal endof the filler tube and the proximal end of the carrier tube being insealing engagement; and a withdrawing device attachable to the assemblyso that, when the withdrawing device and material dispenser is attachedand the component of the tissue prosthesis is mounted on the distal endof the carrier tube, a closed system is formed which allows thewithdrawing device to be used to increase the volume of the closedsystem to form a low pressure region at least in the component.

In certain exemplary embodiment disclosed herein, tissue prosthesisinsertion systems may be provided which include a working cannula foraccessing a site in a patient's body percutaneously, in a less invasivemanner for carrying out a tissue prosthesis insertion procedure at thesite; and an obturating device receivable in the cannula for tamping apart of a tissue prosthesis into position after formation of the tissueprosthesis.

The obturating device may comprise a blunt-ended rod slidably receivablein the working cannula.

In certain exemplary embodiment disclosed herein, tissue prosthesiscomponents may be provided which include an envelope of an elasticallydeformable material, the envelope defining an access opening; and a flowcontrol member arranged in the access opening, the flow control memberbeing configured to permit withdrawal of fluid from an interior of theenvelope prior to filling the envelope with a filler material.

In certain exemplary embodiment disclosed herein, prosthesis deliverysystems may be provide which includes a plurality of nested tubes, anoutermost tube of which functions as a cannula in which the remainingtubes are received, the remaining tubes forming part of a prosthesisdelivery apparatus, a wall portion of at least one of the tubes having achange in diameter along its length to mate with a corresponding part ofa dispensing arrangement for use with the prosthesis delivery apparatus.

In certain exemplary embodiments disclosed herein, systems are providedwhich include a plurality of tubes, wherein an outermost tube functionsas a cannula in which the remaining tubes are received, the remainingtubes forming part of a prosthesis delivery apparatus, a wall portion ofat least one of the tubes having a change in diameter along its lengthto mate with a corresponding part of a dispensing arrangement for usewith the prosthesis delivery apparatus.

In some exemplary embodiments, the prosthesis delivery devices mayinclude at least one carry tube which may carry at least one componentof the prosthesis on its distal end and at least one filler tubereceivable in the carrier tube for charging a filler material into thecomponent when the component is located at the desired location. Theprosthesis delivery apparatus may include a connector for connection toa withdrawal device to enable fluid (e.g., air or gas) to be manipulated(e.g., withdrawn) from the component during formation of the prosthesisin situ, the connector being arranged, in use, at a proximal end of theprosthesis delivery apparatus.

In some exemplary embodiments, the prosthesis delivery apparatus mayinclude a displacement device for displacing the component of theprosthesis after it has been charged with the filler material. Thedisplacement device may be a further tube mounted about the carriertube.

In some exemplary embodiments, the prosthesis delivery apparatus mayinclude at least one cover tube to cover the component of theprosthesis, the at least one cover tube fitting over the at least onecarrier tube. The at least one cover tube may include a resilientlyflexible distal portion to accommodate the component of the prosthesis.In certain embodiments, the at least one cover tube may be received overthe displacement device/tube which is mounted about the carrier tube.

In some exemplary embodiments, a wall portion of each of the tubes has achange in diameter along its length. In some exemplary embodiments, thechange in diameter along the length of each tube may be provided by aflared wall portion of each tube.

In some exemplary embodiments, the systems may include a manipulatingarrangement for effecting manipulation of the tubes located within thecannula. The manipulating arrangement may include a rupturing mechanismfor rupturing the cannula for removal. The rupturing mechanism maycomprise a plurality of spaced zones of weakness in a wall of the tubeof the cannula and a gripping device arranged at a proximal end of thetube of the cannula. The gripping device may comprise a plurality ofoutwardly extending tabs which are pulled outwardly to cause rupturingof the zones of weakness of the cannula to facilitate withdrawal of thecannula after placement and positioning of the component of theprosthesis in the cavity or after formation and/or setting of theprosthesis.

In some exemplary embodiments, the systems may include the dispensingmechanism, the dispensing mechanism including a tubular element having adistal end which corresponds with and mates with that part of the wallportion of the at least one tube having the change in diameter. Thenested tubes may be configured to extend proximally of the distal end ofthe element to overlie the element. With this arrangement, the length ofthe unsupported ends of the tubes is shortened thereby improving therigidity of the tubes and the stability of the system. In addition, thebalance of the system is improved rendering it easier for the clinicianto control the system. This overall reduction in the length of thedelivery system may also result in a reduction in the pressure requiredto deliver the filler material to the envelope component of theprosthesis.

The dispensing mechanism may include a dispenser to which the element isattachable. The element may be a static mixer.

In certain exemplary embodiment disclosed herein, prosthesis deliverysystems are provided which include a plurality of nested tubes, one tubebeing a carrier tube which carries at least a component of a prosthesisat its distal end and another tube constituting a delivery tube fordelivering the nested tubes to a site at a patient's body; and a covertube forming part of the nested tubes, the cover tube being arrangedoutwardly of the carrier tube to cover the component when the carriertube is inserted into the delivery tube to protect the component.

In certain exemplary embodiments disclosed herein, there is provided anintroducer for introducing an intervertebral disc implant into a discthat has undergone a nucleotomy, the introducer including at least twosleeves arranged telescopically with respect to each other; and adisplacement mechanism arranged on an operatively inner surface of aninnermost one of the sleeves for assisting in displacing filler materialalong the sleeves into an interior of the disc, in use.

The displacement mechanism may comprise a ratchet arrangement for urgingthe filler material along the sleeve.

In certain embodiments disclosed herein, equipment may be provided forpreparing a site for the implantation of tissue prosthesis. Theequipment may include, for example a conduit assembly; an elasticallystretchable and/or an inflatable member receivable on a distal end ofthe conduit assembly, the inflatable member being positioned, in use, ata site in a patient's body at which a tissue prosthesis is to beimplanted; and a plurality of fluid dispensers connectable to theconduit assembly to communicate with the inflatable member, operation ofthe fluid dispensers manipulating the inflatable member to facilitateformation of the tissue prosthesis at the site.

Manipulating the inflatable member may comprise priming the inflatablemember to receive a volume of fluid (e.g., a liquid or gas) to determinea size of the site. Still further, manipulating the inflatable membermay comprise cyclically inflating and deflating the inflatable member tocondition tissue surrounding the site.

The equipment may include a monitoring mechanism for monitoring a volumeof fluid dispensed by a selected one or more of the fluid dispensersinto the inflatable member to determine a size of a cavity at the siteto be filled by the tissue prosthesis. In this manner, the inflatablemember may act as a mock implant and may also determine the relativeposition of the implant as well. In certain exemplary embodiments, themonitoring device may be a pressure transducer. It will, however, beappreciated that other transducers such as force transducers, straingauges, or the like could be employed to function as an end-pointmonitor. Alternatively, in embodiments where at least the volume ofnucleus removed, or the volume created by the nucleotomy procedure, isreplaced. Accordingly, the device may allow the volume to be measuredwhich allows the surgeon to gauge the required volume of biomaterial tobe dispensed into the envelope component of the implant.

In certain embodiments, the conduit assembly may comprise at least onetube on which the inflatable member is mountable with a branchedconnector being carried at a proximal end of the at least one tube, oneof the fluid dispensers being connectable to each branch of theconnector. The branched connector may be for example, a Y connector or aT connector.

In certain exemplary embodiments, the conduit assembly may comprise apair (e.g., at least 2, 3, 4, 5, 6, 7, 8, etc.) of nested tubes, anouter tube being a carrier tube on which the inflatable member iscarried and an inner tube being a fluid delivery tube for dispensing avolume of fluid from one of the dispensers into the interior of thetube. In certain embodiments, at least one of the tubes may extend, inuse, to a distal end of the inflatable member and the tube may have anaperture defined in it which facilitates fluid communication between aninterior of the inflatable member and an interior of the tube or tubes.The at least one tube extending into the inflatable member may, incertain embodiments, serve to allow the inflatable member to becollapsible about the tube and more easily introduced percutaneously orminimally invasively through the working cannula.

In another exemplary embodiment, the conduit assembly may comprise asingle tube on a distal end of which the inflatable member is carried. Aflow control member may be received in communication with an interior ofthe tube for placing a selected one of the fluid dispensers in fluidcommunication with the interior of the tube and hence the interior ofthe inflatable member as desired. Similar to other exemplaryembodiments, the tube may extend, in use, to a distal end of theinflatable member and have an aperture defined in it which facilitatesfluid communication between an interior of the inflatable member and aninterior of the tube.

In certain embodiments, the flow control member may be a device whichcontrols the direction and flow of fluid. This can be, for example, a3-way stopcock, or it can be a valve which opens up when the fluiddispenser is engaged, and shuts off when the fluid dispenser isdisengaged (e.g., a duck bill valve). For example, with a duck billvalve, when the fluid dispenser is engaged, the tip of the fluiddispenser pushes open the leaflets of the valve, placing the interior ofthe tubes and inflatable component in fluid communication with the fluiddispenser. When the fluid dispenser is disengaged, the leaflets of thevalve. Such an apparatus using this form of valve system can omit theneed for the dual syringe system because a single syringe can be used toprime the system and any air or gas or other unwanted fluids which aredisplaced from within the system and into the syringe can be purged byremoving the syringe from the rest of the apparatus and purged bymanipulating the piston of the syringe. In the meantime, the fluidwithin the system is maintained within the system because of the valvewhich has closed off to substantially seal in the fluid which has beenused to displace the unwanted air, gas or other fluid which wasoriginally within the system.

At least one of the fluid dispensers may be a reciprocally operabledevice such as for example, a syringe.

In certain exemplary embodiments disclosed herein, there may be providedmethods of preparing a site for the implantation of tissue prosthesis.The methods may include inserting a member into a cavity at a tissuesite to be prepared; priming the member; and inflating the member atleast once with a volume of fluid to determine a size of the cavity.

In certain exemplary embodiments disclosed herein, there may be providedmethods of preparing a site for the implantation of tissue prosthesis.The methods may include means for inserting an inflatable member into acavity at a tissue site to be prepared, means for priming the inflatablemember; and means for inflating the inflatable member at least once witha volume of fluid to determine a size and/or position of the cavity.

The method may include priming the inflatable member prior to insertinginto the cavity which may entail priming the inflatable member prior toinserting the inflatable member into the patient's body. In certainexemplary embodiments, the method may include inflating and deflatingthe inflatable member a number of times to condition tissue surroundingthe cavity. In certain exemplary embodiment, the method may includemonitoring a predetermined parameter to determine the quantity of fluiddispensed into the inflatable member to fill the cavity.

The method may include means for priming the inflatable member prior toinserting into the cavity which may entail priming the inflatable memberprior to inserting the inflatable member into the patient's body. Incertain exemplary embodiments, the method may include means forinflating and deflating the inflatable member a number of times tocondition tissue surrounding the cavity. In certain exemplaryembodiments the method may include means for monitoring a predeterminedparameter to determine the quantity of fluid dispensed into theinflatable member to fill the cavity.

In certain exemplary embodiments disclosed herein, tissue prostheses areprovided which comprise at least one envelope of a biologically inert,elastically deformable material capable of being expanded to conform toan interior surface of a cavity formed at a site in a patient's body;and a filler material received in a fluent state in the at least oneenvelope, the filler material being of the same class of material as theat least one envelope to form, when cured, together with the envelope, aunified, or substantially unified, structure.

In certain exemplary embodiments disclosed herein, tissue prostheses areprovided which comprise an envelope of a foraminous, chemically inertmaterial shaped to conform to an interior surface of a cavity formed ata site in a patient's body in which the envelope is to be placed, and afiller material received in a fluent state in the envelope, the fillermaterial being of an elastomeric material which, prior to being cured,is urged into foramens of the envelope to form an integrated structurewhich inhibits relative movement between the envelope and the fillermaterial, in use, and once the filler material has cured.

In certain exemplary embodiments, there is provided an intervertebraldisc implants which includes an envelope constructed of at least onestretchable and/or elastically deformable elastomeric material, theenvelope including an attaching formation for attachment to anintroducer to enable the envelope, in a first state, to be introducedinto a volume of an intervertebral disc that has undergone a nucleotomy;and a filler material receivable in the envelope via the introducer tocause the envelope to expand elastically to conform substantially to thevolume in which the envelope is received, in use.

According to certain exemplary embodiments, there is provided anintervertebral disc implant which includes a first object constructed ofat least one stretchable and/or elastically deformable elastomericmaterial, the first object being in communication with second object forattachment to a third object to enable the first object, in a firststate, to be introduced into a volume of an intervertebral disc that hasundergone a nucleotomy; and a material receivable in the first objectvia the second object which results in expansion, or partial expansionof the first object such that the first object substantially conforms tothe volume in which the first object is received, in use.

According to certain exemplary embodiments, there is provided anintervertebral disc implant which includes an envelope constructed of atleast one stretchable and/or elastically deformable elastomericmaterial, the envelope including means for attaching an introducer toenable the envelope, in a collapsed state, to be introduced into avolume of an intervertebral disc that has undergone a nucleotomy; andmeans for introducing a filler material into the envelope via theintroducer to cause the envelope to expand elastically to conformsubstantially to the volume in which the envelope is received, in use.

In certain exemplary embodiments, there is provided an intervertebraldisc implant which includes an envelope, the envelope including anattaching formation for attachment to an introducer to enable theenvelope, in a collapsed state, to be introduced into a volume of anintervertebral disc that has undergone a nucleotomy; and a fillermaterial receivable in the envelope after placement of the envelope inthe volume of the disc, in use, to cause expansion of the envelope toconform to the volume, the filler material comprising a plurality ofdiscrete, elongate elements introducible, via the introducer, into aninterior of the envelope.

In certain exemplary embodiments, there is provided an intervertebraldisc implant which comprises an envelope receivable in a volume of anintervertebral disc that has undergone a nucleotomy, the envelopedefining a plurality of chambers, the chambers being configured so that,when at least certain of the chambers contain a filler material, theenvelope conforms substantially to the volume of the disc; a fillermaterial receivable in the at least certain of the chambers; and atleast one of the chambers having a filler mechanism associated with it.

One advantage of certain disclosed methods and equipment are that theyfacilitate minimally invasive formation of tissue prosthesis in situ.Another advantage of certain disclosed methods and equipment are thatthey facilitate percutaneous formation of tissue prosthesis in situ. Inaddition, tissue prosthesis is provided which are resistant todelamination. In particular, in the case where the tissue prosthesis hasan envelope and filler material of the same class of material, asubstantially unified, integrated structure may be provided which isresistant to delamination and relative movement between the envelope andthe filler material. The unified structure and the fact that theenvelope is elastically deformed and is retained under tension alsorenders the envelope resistant to creasing increasing the operationalefficiency of the prosthesis by being better able to distribute forcesto the annulus fibrosis of the disc.

In addition, the use of a silicone rubber envelope in certainembodiments is particularly advantageous due to the fact that, when anucleotomy has been performed, residue remains behind which is irregularin shape. It is beneficial to have a prosthesis which expands andconforms as closely as possible to the shape (micro and macrostructure)of the cavity in order that compressive, tensile, bending and torsionalforces can be accommodated by the disc. In addition, the provision of atissue prosthesis expanding and closely conforming to the shape of thecavity results in an improvement in stimulation and deformation of theend plates of the vertebrae and thereby aiding in restoration of thenatural pumping action which assists in the influx of nutrients and theefflux of waste products from within the disc.

It is yet a further advantage of certain embodiments that the tissueprosthesis can be formed in situ in a minimally invasive manner. Theneed for invasive surgical procedures is therefore obviated and there isthe added advantage of more rapid post-operative recovery and thereduced need for a prolonged period in hospital.

In certain embodiments, the equipment further provides an efficient,easy to use manner of forming the tissue prosthesis. By having the tubesetc. nested, a clinician is more easily able to manipulate the equipmentto place and form the tissue prosthesis. With the added use of a workingcannula, the access to the disc and hence the nucleus pulposus need onlyto be established once. All the remaining tubular apparatus forpositioning and forming the tissue prosthesis are slidably receivablewithin the protected confines of the working cannula. Therefore, thereis no repeated movement of having to go in and out of the tissue whichcould increase the risk of damage to muscle, subcutaneous tissue andparticularly nerves. Further, the use of a barreled dispensing deviceconnected to a static mixer and tube which delivers the mixedbiomaterial directly into the envelope avoids the use of complex systems(for example, ones with pressure feedback etc.) for injecting thematerial which may be used to overcome the changes in pressures whileinjecting into confined tissue spaces.

It is yet a further advantage that the procedure is not restricted tolarge hospitals requiring costly operating tools in the hand ofprofessionals like spinal surgeons, neurosurgeons and orthopedicsurgeons: but can be performed by numerous physician including painphysicians, radiologists, anesthesiologists, sports physicians and anyother professional confident of using a fluoroscope imaging device andplacing needles into intervertebral discs. The larger community andsocietal benefit of such superiority of the present inventions are greatas it improves access and affordability to a large population of chronicback pain sufferers. Other advantages include at non-heat generatingcatalytic interaction (or in certain embodiments, the reaction may beslightly endothermic or slightly exothermic) for polymerization of theflowable material, obviating the risk of thermal damage to adjacenttissues. More advantages include, prevention of leakage of flowablematerial into undesirable confines in the event the prepared tissueswalls have fissures and or breaches that communicate to areas wherethere may be organs at risk.

While the inventions described herein are described with reference tocertain exemplary embodiments related to intervertebral disc nucleusreplacement, it will readily be appreciated by persons of ordinary skillin the art, in view of this disclosure, that the inventions disclosedherein are not limited to such embodiments and that the inventionsdescribed herein are more generally related to tissue prostheses.

In certain exemplary embodiments, the filler material may be anynatural, synthetic or biological polymer. The materials may be polymersor copolymers. The material should preferably present with biocompatiblecharacteristics. The material may at least closely mimic and or at leastclosely restore the function of the joint or tissue it is replacing. Inthe case of the intervertebral disc, the material may restore thebiomechanics of the joint by restoring the intradiscal pressure andhence the hoop stresses to the annulus fibrosis. Should it be required,the material may also be able to supply sufficient pressure to the discto restore any loss in disc height or at least maintain the disc height.The material may also have some load bearing capabilities. Patientsundergoing nucleus prosthesis treatment may have a mildly compromisedannulus fibrosis (small tears and or fissures), hence the prosthesis maybear some of the axial load, whilst still sharing and distributing someof the incident load to the annulus to keep it in tension (i.e., be bothload bearing and load sharing). Also, the material should preferably notinhibit the flow of nutrients and other such fluids through the disc, asthe residual (remaining) nucleus and annulus still requires hydrationand nutrients to at least slow down or halt the degeneration of thedisc. The material may also possess resilience, viscoelasticity andfatigue resistance (as the disc is loaded cyclically during everydayactivities, the disc needs to be able to retain or at least restore itsheight under cyclic fatigue). The class of materials which suits thesefeatures are elastomers, in particular silicones. Silicones have anestablished history of use. They are extremely stable (mechanically andbiologically) in its cured form and even when they are cured in situ,the catalysts used to cure the material are not harmful to thesurrounding tissue and the curing process is harmless to the surroundingtissue. Silicones are resilient, elastic and have excellent shockabsorbing capabilities.

Although the range of hardness for the silicones (or elastomer ingeneral) which are suitable for this application are between about 5-90A (e.g., 5-15 A, 15-20 A, 20-40 A, 40-50 A, 50-70 A, 70-90 A, etc.), thepreferred hardness range is about 20-40 A and more specifically about 30A (e.g.; about 27, 28, 29, 30, 31, 32, 33, etc.). Since silicones deformelastically under a given load, it spreads the load evenly across theendplates and minimizes stress concentration and or stress shieldingwhich could all lead to subsidence of the implant into the endplate.

Additionally, the filler material may have varying degrees of porosity(such as silicone foams). Porosity may allow for tissue to grow into it,it may not affect the flow of nutrients across the disc, and byadjusting the porosity, the mechanical characteristics of the materialmay also be varied (such as deformation under load, creep, fatigueproperties etc.).

The filler material may be selected to at least partially mimic naturalbiomechanical characteristics of the nucleus pulposus of the disc.

The at least one envelope may be made from an elastomeric material,preferably a silicone, which is biologically inert and which canelastically deform up to 3, 5, 7, 10, 30, 50, 80, 100, 120, or 150 timesthe size of the at least one envelope in its relaxed state. In someembodiments, the at least one envelope may be made from the siliconerubber material which is substantially biologically inert and which canelastically deform in the ranges of 3 to 5, 5 to 7, 7 to 10, 10 to 50,10 to 100, 20 to 150, 30 to 100, 20 to 120, 70 to 100, or 50 to 150times the size of the at least one envelope in its relaxed state. Inother embodiments, the envelope may be compliant (e.g., with or withoutbe elastic) which may allow the envelope to conform or substantiallyconform to the cavity.

The at least one envelope may also be made of other materials. Forexample, the at least one envelope made from less expansible materialsuch as a biological or a synthetic polymeric material. A suitablesynthetic polymeric material may, for example, be polyester such aspolyethylene terephthalate (PET). The at least one envelope may also beconstructed of a knitted PET material so that, when the filler materialis charged into the at least one envelope, the filler material fillsforamens or interstices in the at least one envelope to form anintegrated structure which resists relative movement between the fillermaterial and the at least one envelope. Alternatively, the knitted PETmaterial may be coated with silicone allowing the filler material tointegrate with the coating.

The materials which the envelope may be made from may be any natural,synthetic or biological polymer or copolymer which possessesbiocompatibility. The envelope may be a porous material which allows forthe surrounding tissue to grow into the implant and anchor or stabilizethe implant within the disc space for in general at the tissue sitewhich it is being implanted into). The porosity may also allow for thefiller material to seep through the envelope and bond to the envelope toform a substantially fled structure. Should the envelope be made of anon-porous material, the advantage is that it prevents filler materialfrom seeping into unwanted fissures, cracks and tears in the annulus.Even if the envelope is non porous, having filler and envelope of thesame class of materials can also achieve the same substantialunification. Having a unified structure means that there is no relativemovement between the filler and envelope, thus reducing the wear andhence the wear particles being produced. An advantage of having anenvelope of an elastic, resilient material such as silicone is that theenvelope may be capable of expanding and conforming to the macro andmicro structures of the interior of the disc. This also increases thecontact area of the implant across the endplates reducing stressconcentrations and thus reducing the chances of implant subsidence.

As used in the specification the performance of a nucleotomy on the discinvolves the removal of a certain amount of the nuclear tissueconstituting the nucleus pulposus. The methods, devices, and/or systemsdisclosed herein often refer to the removal of the nuclear tissue. Theamount of nuclear material removed may vary from procedure to procedureand this will be understood by those skilled in the art in view of thepresent disclosure. Using the devices, methods, and/or systems disclosedherein, it may be desirable to completely remove the nuclear tissue, inother instances it may be sufficient to substantially remove the nucleartissue, or in other instances it may be sufficient to partially removethe nuclear tissue.

Depending on the degree of nucleus pulposus removal, the prosthesis maybe classed as a total nucleus replacement or a partial nucleusreplacement. Regardless of the degree of tissue removal, the one or moreimplants may completely or at least partially fill the cavity whichremains. Completely filling the cavity will allow the transfer of loadonto the annulus and restore the hoop stresses which are necessary tominimise the shear stresses on the annular layers and hence, at leastslow further degeneration of the disc. If the implant were to partiallyfill the space, it allows the implant to reposition itself in a mannerwhich prevents further migration and minimise the chances of extrusion.It may also reposition itself to a position which is of least resistanceand hence minimise the stresses on the implant and surrounding tissue.The kangaroo data detailed later demonstrates the restoration of thekinematics of the spine even after the partial filling of the nucleuscavity.

One of the advantages of the implant is that multiple units can beimplanted from various directions to achieve a partial, near complete orcomplete filling of the nuclear space. For example, one device can beimplanted on the right side from the right posterolateral corner or theright lateral corner or anteriorly. The other one can be implanted fromthe opposite side as well.

In certain embodiments, a percutaneous approach as opposed to open orminimally invasive surgery may be used. With a percutaneous approach, aneedle is usually used for intravenous injections, intramuscularinjections or intradiscal injections. For minimally invasive surgery,some operations have been described and defined as requiring 1.visualization; which may be magnified by using optical loops, endoscopiccameras, microscopes etc. 2. illumination which is obtained either viacold light sources, optical cables or other means 3. retraction;retraction of tissues is an important components of minimally invasivesurgery as a lot of resources and effort have gone into developing thisthird and final component of minimally invasive surgery. It isunderstandable that a small incision may be required for minimallyinvasive surgery (e.g., about 5 cm, about 6 cm, about 7 cm, etc.) andsuch incisions can be multiple in nature. The present inventors proposethe percutaneous surgery which is carried out without the aid of opticalvisualization, illumination, or the use of any specialized retractors asis required for minimally invasive surgery. In certain embodiments themethod may be performed as a micro-invasive surgery. For example, incertain embodiments, the opening used may be less than 4 cm. Forexample, the opening (e.g., the incision, puncture, or other means ofaccessing the body) may be up to 200 microns, or up to 400 microns, orup to 800 microns (e.g., about 200, 250, 300, 350, 400, 450, 500, 550,600, 650, 700, 750, or 800) or alternatively of the order of about 2 cmto about 4 cm (e.g., about 2, 2.5, 3, 3.5, 4) or alternatively, of theorder of up to 1 cm.

The methods and apparatus defined for formation and insertion of tissueprosthesis can be used in many clinical scenarios in varying fashions.In the area of degenerative disc of the spine, advanced stage discdiseases require the application of posterior spinal fusion with orwithout decompression with the fusion either being static or dynamic. Insituations where the fusion is dynamic and performed with the use ofpedicle screws there is a risk that the lordosis of the motion segmentmay be compromised. In static fusions, the lordosis is recreated by useof an interbody cage or interbody fusion device and the operation iscalled posterior interbody lumbar fusion. In dynamic fusions, the CPDRDcan be implanted in an interbody manner within the nucleus to recreatethe hunbar lordosis, to share load bearing anteriorly and therebyprevent loosening of the pedicle screws. This method may be a preferablemethod of performing posterior dynamic fusion of the spine, usingexisting systems like Dynesis, N-Flexrod (Spine next).

Further, in more advanced disc disease, the clinical condition of spinalstenosis exists where the gap between the spinous processes decreases.In these patients, the classical older operation has been laminectomy,foraminolaminectomy, posterior spinal decompression. More modernoperations include implantation of the Wallis device. X-Stop, or InSpace, Diam. However, these interspinous distraction devices havenumerous disadvantages including incisions to expose the area (minimallyinvasive spinal surgery), and/or being hard and not allowing for shockabsorption. The device disclosed herein can be implanted in theinterspinous area in a percutaneous manner after clearing theinterspinous area with the patient in a flexed position. The distractionof the interspinous area leads to effective improvement in the spinalstenosis. The same interspinous implant can be used after discectomiesperformed for herniated nucleus pulposus fragments either by smallincision or endoscopically.

In certain embodiments, an apparatus for forming a tissue prosthesis(e.g. a disk prosthesis) in situ in a patient's body may be provided.The apparatus may comprise, an inflatable component and a deliverymechanism for delivering a filler material into the inflatable componentso that when the filler material is cured, a unified prosthesis isformed. In certain embodiments, the delivery mechanism may comprise atleast one priming mechanism a hole, valve, or opening) proximate to thearea where the inflatable component is coupled to the delivery mechanism(see, for example, FIG. 386 for an example of a hole 1010 on either sideof the delivery mechanism and proximate to an end of the deliverymechanism). The at least one hole may be large enough for gas to passthrough but small enough so that the filler material cannot passthrough. In this manner, it may be possible to prime the apparatus toremove a substantial amount of the gas from within the system so thatthe gas does not need to be purged when the delivery system is in thebody.

Certain embodiments may provide a method system or apparatus thatcomprises any of the details disclosed throughout this specificationexclusive of for example, a bone grafting, stabilization, or fasteningand/or holding devices such as screws (e.g., facet screws, and/orpedicle screws), staples, etc. For example, in certain embodiments, amethod may be provided that consists only of accessing the site in thebody of a patient (e.g., a vertebral disk), removing tissue from thesite to form a cavity, if necessary, inserting an inflatable componentinto the cavity, and delivering, via a delivery mechanism, a fillermaterial into the inflatable component so that when the filler materialis cured, a unified prosthesis is formed. The exemplary method mayoptionally include some of the additional steps disclosed throughout thespecification. In certain embodiments, a method for completing theimplantation of a tissue prosthesis in situ in a patient's body may beprovided and the method may consist exclusively of accessing the site inthe body of a patient; optionally, removing tissue from the site to forma cavity; optionally, priming a delivery mechanism with filler materialto remove gas from within the delivery system; optionally, sizing thecavity; inserting an inflatable component into the cavity; delivering afiller material into the inflatable component so that when the fillermaterial is cured, a unified prosthesis is formed; and completing theprocedure by removing the delivery mechanism from the site in thepatient's body and optionally, applying a bandage to the site. Incertain embodiments, the method may not require a bandage but may merelybe completed without the use of any mechanical closing means such as forexample, sutchers or stitches.

Certain embodiments may provide a method for forming a tissue prosthesisin situ in a patient's body. The method may comprise accessing the sitein the body of a patient (e.g., a vertebral disk), removing tissue fromthe site to form a cavity, if necessary, and priming a deliverymechanism with filler material to remove gas from within the deliverysystem. The method may further comprise inserting an inflatablecomponent into the cavity, and delivering, via a delivery mechanism, afiller material into the inflatable component so that when the fillermaterial is cured, a unified prosthesis is formed.

In certain embodiments, the delivery mechanism may be configured to beprimed prior to forming the tissue prosthesis and the inflatablecomponent may be deflated during the priming so that after the deliverymechanism is primed, there is an acceptable amount of gas (e.g.,substantially no gas or a minimal amount of gas) in the inflatablecomponent, thereby further eliminating the need for a gas removal systemduring delivery of the filler material (e.g., a two lumen system such asdiscussed elsewhere herein). In certain embodiments, the openingdiscussed above may be used to remove the gas. In particular, as thefiller material fills the delivery mechanism, the gas within the systemmay be pushed out through the hole. In this manner, only a desirableamount of gas may remain in the delivery mechanism. In certainembodiments, the inflatable component may be at least partially primedwith filler material. Partially priming the inflatable component mayinclude partially filling the inflatable component in a manner such thatthe inflatable component remains in a relaxed state or alternatively ina state where it may still be inserted into the site of the body withoutsubstantially more difficulty than if the inflatable component was notprimed (e.g., readily inserted into the working cannula after priming).

In certain embodiments, delivery mechanism and inflatable component mayform a closed system or in certain embodiments, the delivery mechanismand inflatable component may form an open system. An open system is onewhere matter and or energy can flow into and or out of the system. Asystem that receives inputs of energy and or matter and then outputsmaterial into surrounding environments is termed an open system. Incontrast, a closed system is where energy can enter or leave but mattermay not. A system that is shut off from the surrounding environment andis self-contained is termed a closed system. More specifically, a closedsystem may be enclosed by barriers which prevent the influx of materialand also efflux of material. The volume, pressure and or temperature arestill able to change, but, fluid and or other matter are not in directfluid communication with the surrounds external to the bounds of theclosed system.

In certain embodiments, the site within the body of the patient may beaccessed in a minimally invasive manner, percutaneously, or in amicro-invasive manner. Additionally, the diameter of the access pointfor accessing the site within the patient's body may less than 6 cm,less than 5 cm, less than 4 cm or less than 3 cm, less than 2 cm lessthan 1 cm, less than 0.75 cm, less than 0.6 cm, less than 0.5 cm, orless than 0.4 cm. In certain embodiments, the access point through theskin for accessing the site within the patient's body may besufficiently small so as not to require anything more than a bandage. Incertain embodiments, the access point may be sufficiently small so asnot to require any closing device such as for example, stitches,sutures, or a fastening bandage upon termination of the surgicalprocedure.

In certain embodiments, the filler material may have a shore hardness ofless than about 10 A, between 10 to 20 A, between 20 to 30 A, between 30to 50 A, between 50 to 70 A or greater than 70 A, but preferably about30 A. In certain embodiments the filler material may be CSM-2186-14,manufactured by Nusil Technologies or MED5-4230, manufactured by NusilTeclhnologies. In certain embodiments, the inflatable component may bemade from liquid silicone rubbers. Examples include, but are not limitedto, MED-4805, MED-4810, MED-4820, MED-4830, MED-4840 manufactured byNusil Technologies. In certain embodiments, the inflatable component maybe made from high consistency elastomers. Examples include, but are notlimited to MED-2174, MED4-4515, MED-4520, MED-4535 manufactured by NusilTechnologies. In certain embodiments, the inflatable component may bemade from dispersions. Examples include, but are not limited toMED-2214, MED-6400, MED-6600, MED1-6604, MED-6605 manufactured by NusilTechnologies.

Certain embodiments may provide a tissue prosthesis comprising: aninflatable component; and a filler material received in a fluent statein the inflatable component, the filler material being of an elastomericmaterial with a shore hardness of less than 90 A and preferably about 30A. In certain embodiments the filler material may be CSM-2186-14,manufactured by Nusil Technologies or MED5-4230, manufactured by NusilTechnologies. In certain embodiments, the inflatable component may beMED-4830, manufactured by Nusil Technologies.

The filler material is a two-part pourable silicone elastomer that curesat room temperature. It contains about 5% BaSO₄ (e.g., about 3%, 4%, 5%,6%, or 7%) in both parts and mixes at about a ratio of 3:1 to 1:3 (e.g.0.5:1 to 1.5:1, 1:1). The viscosity of part A may be about 105,000 cP(e.g., about 100,000 cp, 101,000 cp, 102,000 cp, 103,000 cp, 104,000 cp,105,000 cp, 106,000 cp, 107,000 cp, 108,000 cp, 109,000 cp, or 110,000cp) while the viscosity of part B may be about 71,000 cp (e.g., about65,000 cp, 67,000 cp, 69,000 cp, 71,000 cp, 73000 cp, or 75,000 cp).Additionally, the filler material may have a durometer of about 22-35D2240 (e.g., about 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33 or34), a tensile strength of between 850 to 1200 psi (e.g., about 900 psi,950 psi, 1000 psi, 1050 psi, or 1100 psi), an elongation of between500%-1200% (e.g., about 500%, 550%, 600%, 650%, 700%, 750%, 800%, 850%,900,% or 1000%), and a tear strength of between 80-120 (e.g., about 90ppi, 95 ppi, 100 ppi, 105 ppi, or 110 ppi). The filler material maytypically be filled with inorganic material for example silica, titaniumdioxide, fly ash or other bio-acceptable fillers (e.g. amorphoussilica). These fillers can optionally be surface treated withhydrophilic agents and/or hydrophobic agents. The inorganic fillmaterial may be present in the filler material in amounts between 5 and50 wt. %, (e.g., 10-40 wt. % including 15 wt. %, 20 wt. % up to 30 wt.%, 35 wt. %, 40 wt. %). The inorganic fill material may be present ineither part A or B or both A and B.

The envelope material may typically be a two-part translucent siliconesystem that cures rapidly with no required post-cure. It mixes at abouta 3:1 to 1:3 ratio (e.g., 0.5:1 to 1.5:1 and 1:1). The composition mayhave a durometer of about 25-35 D2240 (e.g., about 26, 27, 28, 29, 30,31, 32, 33, or 34), a tensile strength of between 1100 and 1500 psi(e.g., about 1250 psi, 1300 psi, 1350 psi, 1400 psi, or 1450 psi), anelongation of between 500% and 1100% (e.g., about 550% 600%, 650%, 700%,750%, 800%, 8505, 900%, 950% or 1000%), a tear strength of between 140175 ppi (e.g., about 140 ppi, 145 ppi, 150 ppi, 155 ppi, or 160 ppi),and a stress at 200% strain of between 150 and 200 psi (e.g., about 160psi, 165 psi, 170 psi, 175 psi, 180 psi, 185 psi, or 190 psi).

The silicone used for the filler material or envelope material mayinclude any one of a variety of silicones generally referred tobio-compatible elastomers formed from polysiloxanes orpolyorganosiloxanes which are polymers having the general chemicalformula [R.sub.2SiO].sub.n, where R is any suitable organic group and nis any integer. Such polysiloxanes suitable for these purposes may alsoinclude a broad family of more complex synthetic polymers containing arepeating silicon-oxygen backbone with organic side groups attached viacarbon-silicon bonds. Such complex silicones, or polymeric siloxanes,may be linear, branched or cross-linked, and can be represented by theformula [R.sub.p SiO.sub.4−p/2)].sub.m, where p is 1-3, m<1, and R isany suitable organic group such as alkyl, alkenyl, fluoroalkyl, phenyl,vinyl, hydroxyl, alkoxy, amino or alkylamino or combination of one ormore of these organic groups, e.g., -phenylvinyl. The term silicone asused herein is also meant to include elastomers that are hetero- orcopolymers of the above-described polysiloxanes. The polysiloxanessuitable for the present invention may also have their terminal endssuch as alkyl, alkenyl, fluoroalkyl, phenyl, hydride, vinyl, hydroxyl,alkoxy, amino or alkylamino group or combinations of one or more ofthese organic groups, e.g., -alkylvinyl (this could be part A of atwo-part system). The polysiloxanes suitable for example as acounter-part polysiloxane (e.g., part B) can be modified to includefunctional, active or inactive organic groups for various purposes, suchas to promote crosslinking (for example hydrides or other terminalgroups functional groups suitable for treating with ethylenicallyunsaturated functional groups) or for copolymerization or otherreactions. The two groups undergoing an addition reaction during curing.Such addition reaction can be aided by a Group VIII metal (e.g.,platinum, rhodium, or palladium).

Non-limiting examples of some polysiloxanes include:polydiorganosiloxanes, polyaklysiloxanes, polydialkylsiloxanes,polydimethylsiloxanes, polyaminoalyklisiloxanes, polyaminoalklsiloxanes,polyethyleneglycol-polydimethyl siloxane co-polymers, siliconepolyesters, polysiloxane-polylactone copolymers,polydimethyldiphenylsiloxane, polyalkylsiloxane-polyurethane copolymerswith one or more terminal groups such as alkyl, alkenyl, fluoroalkyl,phenyl, vinyl hydroxyl, alkoxy, amino or alkylamino group or combinationof two, three or more of these groups (e.g., -alkylvinyl).

In certain embodiments, the priming may occur after the inflatablecomponent is inserted into the cavity. In either of these cases, thepriming may be achieved by having a small opening or several smallperforations at some point near the distal end of the deliverymechanism, preferably just proximal to the inflatable member. Thisopening may allow for gases or certain fluids within the deliverymechanism to escape through the opening, but will substantially limitthe flow of the filler material through this opening. The opening mayallow less viscous fluids to pass through the opening easily, butsubstantially limit more viscous fluids from passing through thisopening. Therefore, as the filler material primes the deliverymechanism, the gases or certain fluids within the delivery mechanism maybe pushed out through this opening and limit the entrapment of gas orcertain fluids within the inflatable member. The opening may be a slitor a hole (see, for example, FIG. 95 for an example of a slit 1008 on aside of the delivery mechanism and proximate to an end of the deliverymechanism). In the case of a slit, the width of the slit may be lessthan 0.1 mm, between 0.1 to 0.5 mm, between 0.5 to 1 mm, between 1 to 5mm or greater than 5 mm. In the case of a hole, the diameter may be lessthan 0.1 mm, between 0.1 to 0.5 mm, between 0.5 to 1 mm, between 1 to 5mm or greater than 5 mm. In certain embodiments, the inflatablecomponent is deflated during the priming and preferably maintaineddeflated until at least the delivery mechanism is substantially primed.In either of these situations, after priming, there may be substantiallyminimal quantities of gas or certain fluids in the inflatable component,thereby eliminating the need for a gas removal system (e.g., a secondlumen) during delivery of the filler material. Additionally, in certainembodiments, the inflatable component may be primed during the priming.

In certain embodiments, the body of the patient may be accessed in aminimally invasive manner, percutaneously, or in a micro-invasivemanner. Additionally, the diameter of the incision for accessing thepatient's body may less than 6 cm, less than 5 cm, less than 3 cm orless than 2 cm. In some embodiments, the incision may be less than 1 cm.In certain embodiments, no external stitches would be required to closethe incision or puncture created when the site is accessed.

In certain embodiments, the delivery apparatus may comprise a carriertube for carrying a component of the prosthesis at its distal end. Thereis also a filler tube which is slidably receivable within the lumen ofthe carrier tube with clearance. At some point near the distal end ofthe carrier tube is at least one slit or several small perforationswhich may allow for gases or certain fluids within the deliverymechanism to escape through the opening, but will substantially limitthe flow of the filler material through this opening. The opening mayallow less viscous fluids to pass through the opening easily, butsubstantially limit more viscous fluids, such as the biomaterial, frompassing through this opening. The method of forming the implant in situmay comprise positioning the carrier tube at the desired location withinthe patient's body. Then the filler tube (which may be attached to amaterial dispenser apparatus) is primed substantially with thebiomaterial prior to being inserted into the carrier tube. As the fillertube is inserted into the carrier tube, the volume of gas, or air, orother fluids within the delivery apparatus, are displaced by the volumeoccupied by the introduction of the filler tube. This gas is displacedthrough the perforations at the distal end of the carrier tube. The gaswithin the delivery apparatus may preferably be displaced through theperforations at the distal end of the carrier tube than the annularspace between the carrier tube and filler tube for a couple of reasons.First, the biomaterial may have overflowed from the distal tip of thefiller tube (substantially enough), to form a plug at the tip of thefiller tube as it is introduced through the carrier tube, thereby notallowing gas to flow around and between the carrier tube and fillertube. Second, the resistance to the flow of gas or air is significantlyless through the perforations than through the annular space between thefiller tube and carrier tube.

Whatever the case may be, substantial volumes of the gas, air or certainfluids within the delivery apparatus would have been displaced and onlya small quantity of air entrapment is likely to occur within theimplant. Additionally, if the component of the implant were to bemaintained collapsed (either through a clamping mechanism, or thesheath) throughout the procedure whilst the filler tube is beingintroduced, then removal of the sheath or clamping mechanism from aroundthe component of the implant would result in an even further reductionof air entrapment into the component.

Using the apparatus described in above, a similar method may be used toform the tissue prosthesis. If the filler tube were to terminateproximally to the perforation within the carrier tube, when nested andassembled as it would be in use, the filler tube may not need to beprimed before being introduced into the lumen of the carrier tube. Ifthe resistance to the flow of gas or air at the perforations issignificantly less than that of the annular space between the carriertube and the filler tube, then as the filler material is charged throughthe filler tube, the air or gas may be displaced through theperforations, minimizing air entrapment into the envelope.

In certain embodiments, the means for maintaining the envelope collapsedmay be a sheath which has built in weaknesses in its walls at its distalend. Rather than having to retract the sheath, by delivering thebiomaterial into the envelope, causes a rise in the internal pressure,breaking the sheath open (in the form of e.g., an orange peel opening)and filling the envelope can commence with minimal introduction of airor gases into the envelope. This form of a sheath may be used to allowfor easy delivery of the envelope through the introducer (workingcannula) and rather than having to retract the sheath, any form ofpressure (such as that by inflating the envelope with air) will breakthe sheath open, thereby exposing the envelope within the disc cavity.Preferably however, the sheath will be maintained over the envelopeuntil such time the biomaterial has reached the envelope and as thepressure builds up within the envelope, the sheath breaks open and theexpansion and filling of the envelope can commence (with minimal airentrapment). This apparatus may be applicable in combination with theapparatus and method disclosed elsewhere herein.

The preferred number of mixing elements for the static mixer, to achievean optimal mix and hence an optimal cure characteristics of thebiomaterial, are 12. However, the mixing elements may range up to about5, 10, 15, 20, 25, 30, 35.

Exemplary elements of percutaneous surgery is the development of aseries of nested tubes that may or may not interlock with each other byvarious means which enables the device in its preformed or fully formedstage to be delivered to the tissue site being treated to achieve animplantable status. A component of these nested tubes is a workingcannula which has the advantages of docking and can have elements whichlock the other tubes or the unlocking and unsheathing of a component ofthe prosthesis.

Advantages of the system may include: (1) that it is capable ofachieving compactness with the system and fit lots of components andelements into a small confinement; (2) the compactness of the systemprovides the means for conducting percutaneous, minimally invasiveprocedures; and the working cannula is docked relative to the patientand the tubes which go through the working cannula are locked orlockable or reversibly lockable to the working cannula. This means thatduring the implant positioning, deployment or filling process, theprocedure can be performed in a stable manner and there is nounnecessary or unintentional relative movement during the implantationwhich can damage the tissue and the tissue prosthesis. Additionally,this may help avoid repeated trauma to tissue as instruments go in andout—preventing the crowding of muscles into the path and isolatingstructures like nerves etc—thereby not only protects outerstructures—but internally protects our device. It may also maintain thedeployment of a disc device or prosthesis) in the desired position.Additionally, in certain embodiments, the device and or components ofthe device may be substantially frictionless. If more force is requiredratchets can be built into the wall to crawl the progress of the deviceand or components of the device and or components of the system.

Implant detachment means may include, screw in and screw off of theimplant, chemically dissolve the interface which holds the implant,vibrational detachment, RF (Radio-frequency) or infrared cutter. Othermeans of implant removal include, sliding the implant off the carriertube by utilization of slideably displaceable nested tubes. These can betubular structures. Also, external or internal cutting mechanism on thetubes which can sever the implant from the delivery apparatus. Also,means of twisting and or crimping the neck of the implant. This can bothseal and detach the implant. Also if the means in which the envelope isheld onto the carrier tube is purely an interference fit or frictionfit, or just tight fit, then pulling on the carrier tube can result indetachment of the envelope. Also, the tube can be rotated to detach.Also, another means for detachment of the implant can includelubrication of the interface which holds the implant. There may be apreformed opening or multiple preformed perforations at the distal endof the carrier tube and or filler tube. The perforations on the carriertube may be at or near the implant interface. Once the implant has beensubstantially filled to capacity, the pressure of filling forces thefiller material to seep through these perforations and lubricate theinterface of the implant allowing it to be removed easily. Othersuitable, biocompatible lubricating media may be used in this way orsimilar way to lubricate the interface which holds the implant.

In certain embodiments, a pressure generating apparatus may preventouter bulging of the barrels, counterbalances the thrust force.Alternatively, the barrel may be integrated into the base of thepressure generating apparatus.

Referring to FIG. 1, an intervertebral disc 10D is generally arrangedbetween adjacent vertebrae 12V and 14V. The disc 10D comprises anannulus fibrosis 16A made up of concentric layers of fibrous tissue. Theannulus fibrosis 16A circumscribes a nucleus pulposus 18N of the disc10D, the nucleus pulposus 18N being of soft tissue. The disc 10D issandwiched between end plates 20E of the vertebrae 12V and 14V. Relativemovement between the vertebrae 12V and 14V causes compression of thenucleus pulposus 18N by the end plates 20E. This serves to assist in theinflux of nutrients into the disc 10D and the efflux of waste productsfrom within the disc 10D.

Certain exemplary embodiments disclosed herein provide methods forimplanting an intervertebral disc implant into an intervertebral disk bypercutaneously performing a nucleotomy on the disc, if necessary, toremove a nucleus pulposus of the disc to create a volume. Once thevolume is created, at least one envelope of the implant is inserted intothe volume and an interior of the envelope is charged with at least onefiller material in a manner to allow the at least one envelope to expandto conform substantially, or partially to the volume. Additionally, theinterior of the at least one envelope is closed oft or substantiallyclose off, to retain the at least one filler material within theenvelope. As discussed herein, the filler material may be selected to atleast partially mimic natural biomechanical characteristics of thenucleus pulposus of the disc.

As will be discussed in more detail elsewhere herein, the methods mayfurther include inserting the envelope into the volume using anintroducer by placing the envelope in a collapsed state on a distal endof the introducer and inserted percutaneously through an opening in anannulus of the disc. Further, the opening may be the same opening viawhich the nucleotomy had been performed. The methods may also includecharging the filler material into the interior of the envelope throughthe introducer. Further, the methods may include closing off theinterior of the envelope by sealing a wall of the envelope. In certainexemplary embodiments, the methods may include closing off the interiorof the envelope by the action of withdrawing the introducer from theenvelope. In certain embodiments, the methods may use a minimallyinvasive technique or the percutaneously technique may be combined withthe minimally invasive technique.

In certain exemplary embodiments the methods for implanting anintervertebral disc implant into an intervertebral disc may includepercutaneously performing a nucleotomy on the disc to remove a nucleuspulposus of the disc to create a volume; inserting an introducer into anopening formed in an annulus of the disc; and introducing into thevolume, via the introducer, at least one element which changes from afirst configuration, in which the at least one element is able to beinserted into the introducer, to a second configuration in which the atleast one element conforms substantially to the volume.

The methods may further include using a single element which, in itssecond configuration, conforms substantially or at least partially tothe volume of the disc. Alternatively, the methods may include using aplurality of elements which together, when each such element is in itssecond configuration, conform substantially or at least partially to thevolume of the disc. In the latter case, the methods may include, priorto insertion of the elements in the volume, introducing at least oneenvelope, in a collapsed state, into the volume and introducing theelements into the at least one envelope to cause the at least oneenvelope to expand to conform substantially or sufficiently to thevolume of the disc. The methods may include, after introduction of theelements into the at least one envelope, closing off a filler opening ofthe at least one envelope. Preferably, the methods includes closing offthe filler opening of the at least one envelope by withdrawal of theintroducer from the filler opening of the envelope.

In certain exemplary embodiments, there is provided an introducer forintroducing an intervertebral disc implant into a disc that hasundergone a nucleotomy, the introducer including at least two sleevesarranged telescopically with respect to each other; and a displacementmechanism arranged on an operatively inner surface of an innermost oneof the sleeves for assisting in displacing filler material along thesleeves into an interior of the disc, in use.

The displacement mechanism may comprise a ratchet arrangement for urgingthe filler material along the sleeve.

In certain exemplary embodiments, there may be provided methods ofpreparing a first assembly of a tissue prosthesis system for insertioninto a patient's body, the method, or methods, comprising providing thefirst assembly which comprises a plurality of nested, or partiallynested, tubes, one of the tubes being a carrier tube; mounting acomponent of the prosthesis on a distal end of the carrier tube, thecomponent being of an elastically deformable material or a sufficientlyelastically deformable material, inserting a stiffening member into thefirst assembly so that the stiffening member extends into an interior ofthe component and causing a proximal end of the stiffening member tosealingly engage a proximal end of the first assembly; attaching awithdrawing device to the first assembly so that the withdrawing deviceis in fluid communication with at least the interior of the component;and operating the withdrawing device to reduce the pressure in theinterior of the component to cause the component to collapse about thestiffening member. The stiffening member may allow the retraction of theouter sleeve, which covers the component of the prosthesis, without thecomponent buckling or prevent the total retraction into the carrier tubewhen the syringe is withdrawn to collapse the component.

The method, or methods, may include attaching the withdrawing device toa fluid port of the first assembly in a sealing manner. The withdrawingdevice may be a syringe which is attached by a Luer lock mechanism tothe fluid port of the first assembly. Other withdrawing devices may be avacuum pump, a pre-evacuated container (such as vacutainer), or acontainer with a preformed low pressure environment, or any apparatus(e.g., which has moveable walls allowing for the volume of the system tobe alterable).

After the component has been collapsed, or sufficiently collapsed, aboutthe stiffening member, the method, or methods, may include placing aprotective sheath about the component. The method, or methods, mayinclude placing the protective sheath about the component by sliding theprotective sheath over the component, the protective sheath constitutingone of the tubes of the nested tubes of the first assembly.

Further, the method, or methods, may include treating one of theprotective sheath and the component with a lubricating medium tofacilitate relative displacement between the protective sheath and thecomponent.

Exemplary lubricants may include, but not limited to, media such aswater for injections, 0.9% saline solution, albumin, fat, mineral oil,lipids, silicone oils, etc.

The method, or methods, may include using the withdrawing device to testthe integrity of the combination of the first assembly and the componentand the stiffening member attached to the first assembly. Testing theintegrity may include determining whether the interior of the envelopeis in fluid communication with fluid external to the walls of theenvelope, and/or inspecting whether the system still remains a closedsystem or substantially closed system, or whether it is an open system.The feedback mechanism may have an associated pressure, force or volumemonitor which is capable of indicating whether or not there is a breachof the seal. These monitors may indicate whether there is a loss inpressure, force, volume associated with the applied pressure, force orvolume.

In certain exemplary embodiments, there may be provided methods offorming a tissue prosthesis at a site in a patient's body, the methodsmay comprise providing a first assembly comprising a plurality of nestedtubes, one of the tubes being a carrier tube with a component of theprosthesis carried at a distal end of the carrier tube; inserting thefirst assembly into a cannula placed in the patient's body; magneticallyattaching or engaging a second assembly to a proximal end of the firstassembly; and charging a filler material from the second assembly intothe component and allowing the filler material to set.

The methods may include, initially, preparing the first assembly asdescribed elsewhere herein.

The methods may include, once the distal end of the first assembly is atthe desired location at the site in the patient's body, withdrawing theprotective sheath to expose the component, the component being anenvelope of an elastically deformable material. The methods may alsoinclude activating the withdrawing device as the sheath is withdrawn tosubstantially collapse the envelope, minimizing the contact area betweenthe envelope and the sheath, minimize the friction between the envelopeand the sheath and hence facilitate sliding between the envelope and thesheath.

The methods may include removing a stiffening rod prior to magneticallyattaching the second assembly to the first assembly. Further, themethods may include causing the second assembly to engage sealingly withthe first assembly so that, together with the component and thewithdrawing device, a closed system is formed.

After the second assembly has been attached to the first assembly, themethods may include operating the withdrawing device to create a lowpressure in the component. Further, the methods may include using thewithdrawing device to test the integrity of the system comprising thetwo assemblies and the component attached to the first assembly. Thismay be performed by either withdrawing or pushing forward on the pistonof the withdrawing device and it should also be noted that the integrityof the system can be tested at the stage once the first assembly hasbeen introduced to the desired location in the patient's body (asdescribed above).

The methods may include dispensing the filler material from a dispenserof the second assembly. The methods may also include purging fillermaterial from the dispenser prior to attaching the dispenser to a staticmixer constituting a part of the second assembly. The methods mayinclude, during filling of the component via a filler tube extendingfrom the static mixer, operating the withdrawing device at least tomaintain, or increase, the volume of the closed system. Mixing may alsobe performed dynamically. Also, the parts may be premixed and deliveredrather than being mixed during the delivery (or charging) process. Incertain aspects, the mixing may not be necessary if it is a single partfiller material. The filler material may be a single part, or at least a2 part mixture (i.e., may have 3 parts, etc.). For example, the 3^(rd)component of the mixture may be the initiating catalyst. Alternatively,these initiators for the curing reaction may be coated onto the innersurfaces of the lumen which the material comes into contact. Forexample, the lining of the static mixer, mixing elements, and the lumenof the filler tube may be treated with a platinum catalyst. Certainprimers may contain the catalyst. Therefore the inner lining of theenvelope may be coated/treated with the primer and when the 2 partfiller material enters and fills the envelope, it comes into contactwith the inner lining of the envelope, thereby initiating oraccelerating the cure. Additionally, because it is also a primer, it mayenhance the adhesion between the envelope and the filler material.

The methods may include, after filling the component, detaching thecarrier tube from the tissue prosthesis formed by the combination of thecomponent and the filler material contained in the component. Thecarrier tube may be detached prior to the filler material having curedor set or after the filler material has at least partially set. In someaspects, the carrier tube may be detached prior to the filler materialhaving been partially or substantially cured. The methods may includedetaching the carrier tube from the tissue prosthesis when the requiredpressure has been reached in the component. In the case ofintervertebral disc nucleus prosthesis, the required pressure may bethat which restores the height of the disc to that of pre-surgery, orthat which substantially fills the volume of the disc. However incertain embodiments, pressure may not be a determinant. Another methodmay include the filling of the component being determined by the volume.The volume to be replaced can be determined by visual or mathematicalcalculation of the nuclear area from patients own images, amount ofnuclear material removed, use of a sizing tool, progressive surgeonexperience, use of a software or self learning algorithm that maydetermine the volume of nucleus that either exists or is removed or maybe required to be replaced. The method of determining the nuclear volumecould also use a disc mapping strategy. Additional methods may includethe methods described in International Application No. PCT/AU03/001289,filed on Sep. 30, 2003 entitled “Mapping and Viewing Device for anIntervertebral Disc”, which claimed priority from Australian ProvisionalApplication No. 2002951762 filed on Oct. 1, 2002. The entire contents ofwhich are herein incorporated by reference in its entirety

In certain exemplary embodiments, the methods may include detaching thetissue prosthesis by relative axial motion between the carrier tube anda displacement device of the first assembly. The displacement device maybe a further tube arranged about the carrier tube and the relative axialmotion may be affected by withdrawing the carrier tube relative to thedisplacement device. In certain exemplary embodiments, the methods mayinclude detaching the tissue prosthesis by filling the component withfiller material to the extent that the component is released from thecarrier tube. In a further exemplary embodiment, the methods may includedetaching the tissue prosthesis by manipulating the carrier tuberelative to the component to cause separation of a part of the componentattached to the carrier tube from a remainder of the component, theseparation occurring at a zone of weakness in the component. Themanipulation may involve rotating the carrier tube with respect to thecomponent.

The methods may further include, after formation of the tissueprosthesis, tamping a part of the tissue prosthesis into position.

In certain exemplary embodiments, the methods may also include, beforeplacing the component in position at the site, preparing the site. Themethods may include preparing the site by removing degenerative tissuefrom the site prior to placing the component at the site.

In certain exemplary embodiments, there may be provided methods offorming a tissue prosthesis in situ at a site in a patient's body, themethods may comprise accessing the site in the patient's body; ifnecessary, removing tissue from the site to form a cavity; inserting atleast one envelope of a biologically inert, elastically deformablematerial into the cavity; charging a filler material, in a fluent state,into the envelope to cause the envelope to expand and conform to theshape of the cavity; and allowing the filler material to cure, thefiller material being of the same class of material as the envelope sothat, when the filler material has cured, a unified, or substantiallyunified, prosthesis is formed.

The methods may further include accessing the site by inserting anintroducer through an aperture formed in tissue associated with the siteand removing nuclear tissue, if required, from the site. The nuclearmaterial may be removed by mechanical, ultrasonic, laser, Argon gas orradio frequency ablation, or the like, in combination with suction andirrigation. For example, mechanical removal may be effected by using areaming-type tool. Additional methods may include the methods describedin U.S. Provisional Application No. 60/971,633, filed on Sep. 12, 2007,entitled “Equipment for, and a method of, removing tissue from a site ina patient's body”. The entire contents of which are herein incorporatedby reference in its entirety.

Once the nuclear tissue has been removed, the methods may includechecking dimensions of the cavity so formed. Thus, the methods mayinclude using the at least one envelope, containing suitable markers, tocheck the dimensions and or position of the cavity. This may be effectedby inflating the at least one envelope using a suitable fluid such as awater/saline solution. Instead of using the at least one envelope withmarkers, the method may include using a flexible wire fed down theintroducer and checking the position of the wire using a fluoroscopicx-ray technique once the wire is in position. In a further way ofchecking the dimensions of the cavity, the methods may include deployingat least one jacket of similar dimensions to the at least one envelopein the cavity, inflating the jacket with the water/saline solution and,using a fluoroscope, detecting the periphery of the jacket by radioopaque markers on an outer surface of the jacket.

Once the at least one envelope has been placed in position, the methodsmay include checking the integrity, of the at least one envelope, i.e.to ensure that the at least one envelope does not have any leaks orother defects. This may be effected and affected by filling the at leastone envelope with the water/saline or radiopaque solution.

The methods may include manipulating an interior of the envelope toinhibit the formation or entrapment of fluid bubbles in the fillermaterial. Instead, the methods may include commencing filling of theenvelope from a distal end of the envelope and progressively filling theenvelope towards a proximal end of the envelope (by withdrawing a fillertube or allowing the material buoyancy to lift the filler tube) toinhibit the formation or entrapment of fluid bubbles in the fillermaterial. In the latter case, either a delivery device by which theenvelope is introduced into the cavity or the envelope may define aformation allowing the escape of air, or gas, or certain fluids, as theenvelope is charged with the filler material. It may be desirable, incertain embodiments, to limit the formation or entrapment of bubbles, orto eliminate substantially the formation or entrapment of bubbles, inthe filler material. An advantage of minimizing air or gas or certainfluid bubbles is that it maximizes the volume occupied by thebiomaterial and the less voids (air bubbles) the implant has, it maymaximize the mechanical performance and stability from a fatigue andcreep resistance perspective. Any trapped air may be compressed insidethe envelope.

The methods may include, once filling of the at least one envelope hasbeen completed and a filler element withdrawn, occluding the aperture inthe tissue of the site. Occluding the aperture may comprise closing itoff by a non-return valve or by crimping closed a neck portion of theenvelope. A removable tube may be nested over the delivery device andmay be propelled distally to remove the at least one envelope and valvefrom the delivery device.

The methods may include attaching the at least one envelope to a distalend of a tubular delivery device and everting the at least one envelopeon the distal end prior to insertion of the delivery device into theintroducer for delivery of the envelope into the cavity of the site.

In certain exemplary embodiments, the method, or methods, may includeaccessing the site using an appropriate percutaneous surgical procedure.Hence, the method, or methods, may be used to perform less invasive (ascompared with minimally invasive and/or other surgical procedures)intervertebral disc nucleus replacement and may comprise forming anaperture in an annulus fibrosis of the disc percutaneously; extracting anucleus pulposus of the disc to form a disc cavity bounded by theannulus fibrosis of the disc and end plates of vertebrae between whichthe disc is located; inserting the at least one envelope, in asubstantially relaxed state (or first state), into the cavity throughthe aperture; charging the filler material into the at least oneenvelope to cause (or resulting in) the at least one envelope to expand(or second state) and conform, or substantially conform, to the shape ofthe disc cavity; allowing the filler material to cure to form, togetherwith the at least one envelope, the unified, or substantially unified,prosthesis; and occluding the aperture.

In certain exemplary embodiments, the method, may include accessing thesite using a percutaneous surgical procedure. Hence, the method may beused to perform less invasive intervertebral disc nucleus replacementand may comprise forming an aperture in an annulus fibrosis of the discpercutaneously; extracting a nucleus pulposus of the disc to form a disccavity bounded by the annulus fibrosis of the disc and end plates ofvertebrae between which the disc is located; inserting the envelope, ina first state, into the cavity through the aperture; charging the fillermaterial into the envelope to cause the envelope to expand and conformto the shape of the disc cavity; allowing the filler material to cure toform, together with the envelope, the unified prosthesis; and occludingthe aperture.

In certain exemplary embodiments, the methods include expanding andstretching the walls of the envelope and retaining the envelope undertension after charging it with filler material. In other embodimentswhere the cavity is relatively small, it may not be necessary for theenvelope to expand.

In an exemplary embodiment disclosed herein a method of forming tissueprosthesis, in situ is provided. In the exemplary method, a damagednucleus pulposus 18N of the disc 10D is removed and is replaced by anartificial prosthesis. Thus, as shown in FIG. 1 of the drawings, anintroducer 22I is inserted percutaneously into abutment with the disc10D. An aperture forming element in the form of a trocar 24T is insertedinto a lumen 26L of the introducer 22I. A point 28P of the trocar 24Tpierces the annulus fibrosis 16A of the disc 10D forming an aperture 30A(FIG. 2) in the annulus fibrosis 16A of the disc 10D.

After the formation of the aperture 30A, the trocar 24T is removed fromthe introducer 22I. Once the trocar 24T has been removed, a nucleotomyis performed on the disc 10D. The nucleotomy involves the removal ofsufficient nuclear tissue constituting the nucleus pulposus 18N. Whilevarious methods of removing the nucleus pulposus can be used (examplesof which are discussed throughout the specification), the example hereinshows the use of a mechanical device 32M. The mechanical device 32Mcomprises a reaming tool 34R. The mechanical device 32M is insertedthrough the lumen 26L of the introducer 22I and the aperture 30A in theannulus fibrosis 16A of the disc 10D into the nucleus pulposus 18N. Thereaming tool 34R (FIG. 3) is operated to remove the nucleus pulposus 18Nas shown in FIG. 4 of the drawings so that a cavity 36C remains. Thecavity 36C is bounded by the annulus fibrosis 16A and the end plates 20Eof the vertebrae 12V and 14V. Residue 64R of the nucleus pulposus 18Nremains resulting in the cavity 36C having irregular walls.

In certain embodiments, an envelope 38E of an elastomeric material, moreparticularly, a silicone rubber material is mounted on a distal end of atubular delivery device 40T. The tubular delivery device 40T defines apassageway 42P (FIG. 5). The envelope 38E may be made from the siliconerubber material which is biologically inert and which can elasticallydeform up to for example 3, 5, 7, 10, 20, 30, 40, 50, 60, 80, 100, 120,140, or 150 times the size of the envelope 38E in its relaxed state.

In an exemplary embodiment, as shown in greater detail in FIG. 10, theenvelope 38E, in its relaxed, or deflated, state, is a snug fit over adistal end 44D of the tubular delivery device 40T. A first sleeve 46F isarranged coaxially over the tubular delivery device 40T adjacent thedistal end 44D of the tubular delivery device 40T. This sleeve 46F mayhave a plurality of openings 48O defined in it. These openings 48Ocooperate with openings 50F at the distal end 44D of the tubulardelivery device 40T. A further sleeve 52F is mounted coaxially about thesleeve 46F and communicates with a fluid manipulation device (not shown)via a fluid manipulation tube 57. Proximal ends of the sleeves 46F and52F are sealed against an outer surface of the tubular delivery device40T via seals 56S. A further seal 58F is arranged between a distal endof the sleeve 52F and the sleeve 46F.

When filler material, referenced generally by the reference numeral 60F(and discussed in more detail elsewhere herein), is injected into theenvelope 38E, a low (e.g., lower than ambient) pressure may be,simultaneously, prior to injection, or a combination thereof imparted tothe tubular delivery device 40T and or envelope 38E to manipulate (e.g.,evacuate) fluid, more particularly, gases, from within the envelope 38E.This assists in substantially airless mixing and helps ensure that theformation of gas bubbles in the filler material 60F is substantiallyinhibited. Manipulation of gases also helps inhibit entrapment of gaseswithin the envelope 38E by the incoming filler material 60F andfacilitates the flow of the filler material 60F into the envelope 38E.As the filler material 60F is charged into the envelope 38E through thefilling openings 50F, gas is drawn out of the envelope 38E by operationof the fluid manipulation device via the fluid manipulation tube 57. Thegas is received between the outer surface of the tubular delivery device40T and the sleeve 46F. This gas passes through the openings 48O in thesleeve 46F and through the evacuation fluid manipulation tube 57.

In alternative embodiments (e.g.; open and/or closed multi lumensystems), gas can be removed in other manners as well. For example, thefiller tube could be primed before it is inserted it into the envelope(or carrier) tube and deliver the biomaterial into the envelope.Alternatively, the envelope could be maintained in a collapsed state sothat the envelope does not need to be actively manipulated during anystages of the filling. In other embodiments, a first and second lumenmay be used to deliver fluid (one of course delivers low pressurefluid). The term deliver is not specifically directional towards theenvelope or away from the envelope. In a closed or open system scenario,the filling tube may extend (perhaps half way or all the way to the end)into the envelope and as the envelope is filled, the fluid in theenvelope may be pushed out through a second lumen. In certainembodiments, the filling tube terminates at a point substantially inalignment with the proximal end of the envelope or just proximal to theenvelope. The filling tube may terminate substantially in line with thedistal end of the carrier tube, or just proximal to the distal end ofthe carrier tube. As the filler material is charged into the envelope,evacuation, or manipulation of fluid, or withdrawal of fluid, at leastfrom within the envelope may no longer be active, as the annular spacebetween the first and second lumen, which was in fluid communicationwith the interior of the envelope has been substantially occluded. In asingle lumen filling system, the envelope may be carried by the fillingtube (thereby the filling tube being both the filling tube and carriertube) and the fluid in the envelope may be vented around the space 1016between the filling tube 1014 and a valve 1012 on the envelope (see,e.g., FIGS. 96 and 97). In certain embodiments, a valve may not benecessary, so long as there is some clearance between the envelope andthe outside of the filling tube, fluid will be able to be pushed outfrom the envelope as the envelope fills with a biomaterial.

As shown in FIG. 6, it may also be useful to monitor the shape and sizeof the cavity 36C taking the residue 64R into account. This can beachieved in a number of ways. One of the ways in which this can beachieved is by having radio opaque markers 70R arranged on the envelope38E. Prior to charging the envelope 38E with the filler material 60F,the envelope 38E can be expanded to conform to the shape of the cavity36C by means of a water/saline solution or a radio opaque solution. Themarkers 70R, being radio opaque, are monitored under a fluoroscope todetermine the shape and size of the cavity 36C.

Other methods of assessing the size of the cavity 36C include the use ofa flexible wire inserted down the lumen 26L of the introducer 22I, thewire being monitored by a fluoroscope. Yet a further way of monitoringthe shape and size of the cavity 36C is by use of a dedicated jacket, ofsimilar dimensions to the cavity 36C, which is inserted into the cavity36C and inflated using the water/saline solution or the radio opaquesolution. The jacket carries radio opaque markers which are monitored bya fluoroscope.

FIGS. 77-79 illustrate an embodiment of equipment for preparing a sitefor implantation of tissue prosthesis. The equipment 10E comprises aconduit assembly 12C carrying a member 14M at a distal end of theconduit assembly 12C. The equipment 10E further may also include aplurality of fluid dispensers 16F connectable to a proximal end of theconduit assembly 12C to communicate with the member 14M. In certainaspects, the member may be sufficiently inflatable, resilientlyflexible, able to be elastically deformed, or combinations thereof ofthese properties.

This equipment 10E may be used to determine, or approximate, the size ofa cavity 18C formed in an intervertebral disc 20I. The disc 20I has anannulus 22 surrounding a nucleus 24. Degeneration of the disc 20I mayresult in herniation of nuclear material of the nucleus 24N through theannulus 22A. To repair a damaged disc 20I, the nucleus 24N may bereplaced by an intervertebral disc prosthesis as described in theembodiments disclosed in this specification.

In addition, the equipment 10E may also measure the position of thecavity. The position of the cavity as well as the position of theprosthesis may be checked under the fluoroscope or other imaging meansto check the cavity position laterally and in the anterior-posteriorview (AP view). In other words, the sizing device can be viewed as amock implant. An advantage of sizing the cavity and the position is thatthe remainder of the implant can actually be performed blind without theneed of any imaging assistance. This is because the working cannula willposition the implant and the sizing device has determined for thesurgeon the volume required to fill the implant.

To prepare the site for implantation of the prosthesis, it may bedesirable to conduct a nucleotomy to remove portions, or substantialportions, of the nuclear material from the disc 20I. However, in certaincircumstances, the nuclear material 24N may have either degenerated orherniated through the annulus 22A to a sufficient extent that a cavity18C is formed which can receive the tissue prosthesis to reconstruct theintervertebral disc 20I. The amount of nuclear material that needs to beremoved may be expected to vary from situation to situation.

The member 14M may be made from a number of different materials. Incertain preferred embodiments, it is desirable that the member beinflatable, resiliently flexible andfor able to be elastically deformed.In certain embodiments, the member 14M could be of a silicone materialand may have similar or substantially the same characteristics of theenvelope of the applicant's tissue prosthesis described herein.

In the exemplary embodiment illustrated, the equipment 10E comprises apair of fluid dispensers 16F each in the form of a syringe 26S, 28S. Thesyringe 26S has a barrel 30B and a plunger 32P slidably displaceable inthe barrel 30B. Similarly, the syringe 28S has a barrel 34B and aplunger 36P slidably displaceable in the barrel 34B. Further, in thisembodiment, the conduit assembly 12C comprises a first, outer conduit,or tube, 38O. The member 14M is mounted on a distal end of the outertube 38O. An inner, filler conduit, or tube, 40F is co-axially arrangedwithin the outer tube 38O. The filler tube 40F projects from the syringe26S through a branched connector 42B arranged at a proximal end of thetube 38O. The branched connector 42B may be a Y connector defining aprimary lumen 44P through which the tube 40F extends and a secondary,branched lumen 44P. The syringe 28S is connected to a part 48P of theconnector 42B defining the secondary lumen 46S.

In use, in this exemplary embodiment, the equipment 10E is insertedpercutaneously via a working cannula (not shown in these figures butdescribed elsewhere) so that the member 14M is received in the cavity18C of the disc 20I. The equipment 10E is inserted percutaneously.

Initially, the equipment 10E may be primed. The priming of the equipment10E is effected and affected by drawing on the plunger 36P of thesyringe 28S in the direction of arrow 50A. This may result in the member14M collapsing. Because the equipment 10E defines a closed system, orsubstantially closed system, it also results in the plunger 32P of thesyringe 26S being drawn in the direction of arrow 52A. The syringe 26Scontains a volume measuring fluid. In certain embodiments, the volumemeasuring fluid may comprise non-compressible fluid, and/or fluids, suchas a liquid (e.g., but not limited to, a radioopaque dye (such asurografin), or water or a saline solution). In some aspects, the fluidmay be substantially non-compressible fluid and/or fluids. The equipment10E is regarded as being fully or substantially primed when the liquidfrom the syringe 26S begins to flow into the syringe 28S.

The position of the plunger 36P of the syringe 28S may be fixed inposition as shown in FIG. 78. The plunger 32P of the syringe 26S is thenfurther pushed in the direction of arrow 52A to inflate the inflatablemember 14M fully. Instead of fixing the position of the plunger 36P inthe syringe 28S, can be removed and a sealing cap (not shown) can beplaced over the branch of the Y connector to maintain the closed orsubstantially closed system.

Referring to FIG. 79, the plunger 32P of the syringe 26S may be drawn inthe direction of arrow 54A to deflate the member 14M. Inflation anddeflation of the member 14M using the syringe 26S is then repeated for anumber of cycles to condition the disc 20I. The cyclicalinflation/deflation of the disc 20I increases the laxity of the disc 20Iand is generally referred to as “mobilizing the joint”. By cycling themember 14M a number of times, surrounding residual nuclear material 55Rin the disc 20I may be compressed or compacted and is less likely tointerfere with the subsequently implanted nuclear prosthesis.

Once the disc 20I has been cycled a number of times, the plunger 32P ofthe syringe 26S may be drawn to a start position in which the member 14Mis, once again, substantially collapsed. It will be appreciated that,because the system is a closed system, and the plunger 36P of thesyringe 28S is locke in position, the plunger 32P of the syringe 26Swill only be able to be withdrawn to a certain fixed, start position inthe barrel 30B of the syringe 26S. In this position, the member 14M issubstantially collapsed and the conduits 38O and 40F are filled with gasand/or liquid, respectively, it being appreciated that there will alsobe some liquid in the conduit 38O. Depending on the degree of withdrawalof the piston 36P, conduit 38O may be composed completely orsubstantially of fluid (liquid) also. In this position, the equipment10E is substantially primed.

The plunger 32P of the syringe 26S is urged in the direction of arrow52A to displace the volume measuring liquid from the syringe 26S intothe inflatable member 14M. This fully inflates the member 14M so that itconforms to the shape of the cavity 18C in the disc 20I. When the member14M fully conforms to the cavity 18C, any attempt to further displacethe plunger 32P in the direction of the arrow 52A will result in asubstantial increase in pressure. This is therefore the end pointindicating that the member 14M fully conforms to the cavity 18C of thedisc 20I and the amount of liquid dispensed from the syringe 26S afterpriming of the equipment 10E is an accurate indication of the volume ofthe cavity 18C.

As will be described in the embodiments described below with referenceto FIGS. 80-85, the plunger 32P may carry a transducer (not shown inthis embodiment). The transducer may, for example, be a pressuretransducer and, when the sudden increase in pressure occurs, anenunciator may be activated to indicate the end point.

Referring now to FIGS. 80-85, additional embodiments of equipment forpreparing a site for implantation of tissue prosthesis is described. Inthese embodiments, the conduit assembly 12C comprises a single tube 38Sto which the connector 42B is connected at a proximal end of the tube38S. A distal end of the tube 38S carries the member 14M.

In this embodiment, the connector 42B may be a T-connector defining theprimary lumen 44P and the secondary lumen 46S. It will, however, beappreciated that the connector 42B could, as in the previousembodiments, be a Y-connector.

The conduit assembly 12C further includes a fluid control arrangement inthe form of a three way stopcock 56ST. The stopcock 56ST is operable toplace either, or both, or neither lumen 44P and 46S of the connector 42Bin fluid communication with an interior of the tube 38S or the lumen 46Sof the connector 42B in communication with the interior of the tube 38S.

As in the case of the previous embodiments, the syringe 26S is connectedto the connector 42B to be in communication with the lumen 44P of theconnector 42B. The syringe 28S is connected to the connector 42B to bein communication with the lumen 46S of the connector 42B. In use, inthese embodiments, the equipment 10E may be inserted percutaneously viaa working cannula (not shown).

To prime the equipment 10E, the syringes 26S and 28S are operated. Moreparticularly, the stopcock 56ST is positioned so that the lumen 46S isoccluded while the lumen 44P of the connector 42B is open. The plunger32P of the syringe 26S is urged in the direction of arrow 58A. Thiscauses inflation of the member 14M. Some liquid from the syringe 26Swill enter the member 14M and so will gas which was present in theequipment 10E. The fluid from the syringe 26S, being heavier than thegas, will sink to the distal end of the member 14M. The gas in theequipment 10E will be displaced to be arranged near the distal end ofthe tube 38S.

Withdrawal of the piston 32P of the syringe 26S in a direction of arrow59 will draw out the gas from the tube 38S and, subsequently, fluid fromthe member 14M as well. These steps may be repeated a number of times toensure that the equipment 10E is fully primed. The equipment 10E isregarded as being fully primed when the piston 32P of the syringe 26S isdrawn to the position shown in FIG. 82 in which the member 14M issubstantially collapsed.

It should be appreciated that the priming method described above isapplicable when the inflating member is pointing down (i.e., as it wouldbe the case if the device were positioned in the disc) and the fillingtube/member stops at the proximal junction to the inflation member. Forthe case where the filling tube extends into the distal part of theinflating member, the priming should occur with the inflating memberpointing up (i.e., or as the case may be, primed before being positionedinto the disc). This is because when the fluid is ejected from thesyringe to prime the system, the buoyancy of the gas may force the gastowards the distal part of the inflatable member where the lumen of thetube is.

With the piston 32P of the syringe 26S in the position shown in FIG. 82,the stopcock 56ST is switched to occlude the lumen 44P of the connector42B and to open the lumen 46S of the connector 42B (see FIG. 83). Thisplaces the syringe 28S in communication with the interior of the tube38S and the interior of the member 14M. The syringe 28S contains avolume measuring liquid (e.g., water or a saline solution).

The plunger 36P of the syringe 28S is urged in the direction of arrow60A (FIG. 84) to inflate the member 14M fully so that it substantiallyconforms, or at least partially conforms to the shape of the cavity 18Cof the disc 20I. The plunger 36P of the syringe 28S is then drawn in thedirection of arrow 62A (FIG. 85) to cause deflation of the member 14M.The plunger 36P is cycled a number of times to inflate and deflate themember 14M to condition the disc 20I as described in this specification.

After conditioning the disc 20I, the plunger 36P is drawn to a zeroingposition in the syringe 28S. It will be appreciated that, because theequipment 10E defines a closed system, or substantially closed system,the plunger 36P can only be withdrawn to a certain, fixed position inthe syringe 28S. This position occurs when the member 14M issufficiently collapsed. In this zeroing position, the plunger 36P is,once again, urged in the direction of arrow 60A to inflate the member14M fully so that it conforms, or substantially conforms to the cavity18C of the disc 20I. It will be appreciate that, when the member 14M hasbeen fully or appropriately inflated, further attempts to displace theplunger 36P in the direction of arrow 60A will typically result in asudden or steep increase in pressure. The pressure is recorded by apressure transducer 64P carried on the plunger 36P of the syringe 28S.The transducer 64P is connected to a transducer readout 66S whichcontains an enunciator. The enunciator may be an audible and/or visualenunciator to alert an operator that the end point has been reached andthat the member 14M is fully, or appropriately, inflated. The volume ofliquid displaced from the syringe 28S represents the volume of thecavity 18C of the disc 20I. Since the radioopaque dye being injected issignificantly incompressible, there is a significant difference (steeppressure rise) in the resistance to further displacement of the syringepiston 36P when the member 14M has been inflated to capacity, thus thetactile feedback is a sensitive enough indication in being able to gaugethe endpoint of filling. The feedback which the surgeon receives fromthe resistance of the syringe piston 36P is significantly sensitive forthe surgeon to be able to gauge the endpoint of filling.

In certain embodiments disclosed herein, the conduit assembly 12C mayact as a stiffening member for the member 14M. Thus, in certainembodiments, the filler tube 40F may extend to a distal end of themember 14M as indicated by dotted lines 68D in FIGS. 78 and 80 of thedrawings. The extension 68D of the filler tube 40F has a slot 70 definedin it to place the interior of the member 14M in communication with theinterior of the filler tube 40F to allow inflation and deflation of themember 14M. In these embodiments, when the member 14M is substantiallycollapsed, it is collapsed about the extension 68D of the filler tube38S. Similarly, in the embodiments described with reference to FIGS.80-85, the tube 38S of the conduit assembly 12C may have the extension68D with the slots 70S defined in the extension 68E. In theseembodiments, it may be desirable to prime the equipment 10E externallyof the patient as gas needs to move to a top of the member 14M with theequipment 10E being held vertically so that the member 14M is at the topof the equipment 10E. In such cases, it is desirable to have the slot70S substantially distal. In certain embodiments, the equipment 10,whether with the extension 68D of the filler tube 40F or not, can beprimed when the equipment 10E is positioned within the patient. Ingeneral, the equipment 10E should be able to be primed so that anaccurate measure of the volume of a cavity to receive tissue prosthesiscan be determined. In addition, by cycling the inflatable member, thesurrounding tissue can be conditioned for receiving the tissueprosthesis.

As shown in FIG. 6, after the shape and size of the cavity 36C have beendetermined, the filler material 60F is dispensed from the dispenser 62Dand is monitored via the sensing arrangements 66S or 68S, as the casemay be. As illustrated in FIG. 7 of the drawings, the filler material60F causes elastic expansion or inflation of the envelope 38E so thatthe envelope 38E conforms to the shape of the cavity 36C and bearsagainst the residue 64R of the nucleus pulposus remaining in the cavity36C. The envelope 38E, having been elastically expanded by the fillermaterial 60F, remains under tension around the filler material 60F whileconforming to the shape of the cavity 36C.

Backflow filler material 60F from the interior of the envelope 38E maybe controlled either by a valve 72V as shown in FIG. 13 of the drawingsor by a clamping device 74C as shown in FIG. 7 of the drawings. Thevalve 72V is a duckbill valve and acts as a one way valve so thatbackflow of filler material 60F from the envelope 38E is substantiallyrestricted or inhibited.

Once the envelope 38E has been filled and has expanded so that itconforms closely, sufficiently, and/or substantially to the shape of thecavity 36C and is received snugly in the cavity 36C, the filler material60F is allowed to cure for a predetermined period of time of, forexample, up to about 5, 10, 15, 20, 25 or 30 minutes. After substantialcuring of the filler material 60F, the tubular delivery device 40T isremoved (alternatively, as described elsewhere herein, the tubulardelivery device 40T may be removed after delivery of the filler material60F but before curing) leaving the aperture 30A occluded as shown at 76Oin FIG. 8 of the drawings. The unified tissue prosthesis 100P so formedis preferably, substantially cured after about 10 minutes.

To facilitate removal of the tubular delivery device 40T from theenvelope 38E, the envelope 38E may incorporate a zone of weakness in theform of a circumferential groove 78G (FIG. 14) formed at a proximal end.The zone or area of weakness may be achieved in a number of differentmanners as well, for example, but not limited to, being built in duringthe manufacturing process. As the tubular delivery device 40T iswithdrawn, when its distal end comes into register with the groove 78G,the tubular delivery device 40T is twisted relative to the envelope tocause a break at the groove 78G to form the occlusion 76O in theaperture 30A of the annulus fibrosis 16A of the disc 10D. In certainembodiments, the occlusion 76O may be formed as a result of the annularfibers closing over the aperture after the delivery device has beenremoved.

FIG. 12 shows another way of delivering the envelope 38E into the cavity36C in accordance with certain embodiments. In. FIG. 12, the envelope38E is everted to lie within the distal end of the delivery device 40Tto facilitate its insertion into the cavity 36C. A similar arrangementis shown in FIG. 9 and FIG. 14.

In FIG. 11, another embodiment of equipment for forming the tissueprosthesis 100P is shown. In this embodiment, a filler tube 80F is used.The tube 80F is received in the passageway 42P of the delivery device40T. A sleeve 82S is arranged coaxially about the delivery device 40T. Afirst displacement device, such as a trigger, MT is provided forcontrolling relative movement between the delivery device 40T and thetube 80F. A second displacement device, which may also be in the form ofa trigger. 86T controls relative movement between the delivery device40T and the sleeve 82S.

The equipment, as shown in FIG. 11, is for use where a fluidmanipulating device is not used. Thus, to fill the envelope 38E, thetube 80F is urged towards the distal end of the envelope 38E andcharging of the filler material 60F into the envelope 38E commences atthe distal end of the envelope 38E. Filling of the envelope 38Eprogresses from its distal end towards its proximal end. Thus, as fillermaterial 60F is charged into the envelope 38E, the tube 80F is slidproximally relative to the tube 40T by manipulating the trigger 84T orslides back through buoyancy of the filler material. Once the envelope38E is in its fully inflated state, the envelope 38E is urged off thedistal end of the tubular delivery device 40T by manipulating thetrigger 86T. As the tube BOF is withdrawn from the valve 72V and theenvelope 38E is removed from the distal end of the tubular deliverydevice 40T, the valve 72V closes to form the occlusion 76O. Tofacilitate expulsion of gas when a fluid manipulation system is notbeing used, the envelope 38E has a bead 88B (FIG. 12) formed along thatportion which seats on the distal end of the tubular delivery device 40Tto create passages 90P through which air or gas or certain fluids can bedischarged as the envelope 38E is charged with the filler material 60F.

The envelope 38E may be constructed of a silicone rubber material whichcan be inflated up to about 5, 10, 15, 25, 50, 75, 100, or 150 times itsrelaxed size without rupturing. In certain embodiments, the envelope 38Emay be made of less expansible material such as a biological or asynthetic polymeric material. A suitable synthetic polymeric materialmay, for example, be a polyester such as polyethylene terephthalate(PET). The envelope 38E may be constructed of a knitted PET material sothat, when the filler material 60F is charged into the envelope 38E, thefiller material fills foramens or interstices in the envelope 38E toform an integrated structure which resists relative movement between thefiller material 60F and the envelope 38E. Alternatively, the knitted PETmaterial may be coated with silicone allowing the filler material 60F tointegrate with the coating.

FIGS. 15 to 17 show different shapes of envelopes 38E which can be useddepending on which intervertebral disc 10D is to have its nucleuspulposus 18N replaced. Additional detail regarding the envelopes isprovided elsewhere herein.

FIGS. 18 to 21, show further embodiments of equipment for forming atissue prosthesis, in situ, at a site in a patient's body isillustrated. In these embodiments, the equipment 110E comprises adelivery device in the form of an envelope tube 112E. The envelope tube112E carries the envelope 38E at its distal end.

A filler member in the form of a filler tube 114F is slidably receivedwithin a passage 116P of the envelope tube 112E. As illustrated in FIG.21, the filler tube 114F has a smaller outer diameter than an innerdiameter of the envelope tube 112E to form an annular gap 118A betweenthe filler tube 114F and the envelope tube 112E.

A removal mechanism in the form of a push-off tube 120 is a snug fit onthe outer surface of the envelope tube 112E.

In certain embodiments, the envelope 38E is of a two part constructioncomprising a sleeve 122S (FIG. 21) to which an envelope defining member124E is adhesively bonded as shown by an annular adhesive layer 126A.The sleeve 122S (and hence the valve) may be molded into the envelopedefining member 124E via insert molding or alternatively, the moldedenvelope may include a valvular member. The sleeve 122S defines thevalve 72V. For materials other than silicone, the sleeve 122S may bewelded (hot or cold), insert molded (or overmolded), onto the envelopedefining member 124E. Alternatively, the sleeve 122S and the envelopedefining member 124E may be held together by a friction fit.Combinations of all of the above may also be applicable.

A distal end of the filler tube 114F carries an engaging member 128Ewhich engages and opens the valve 72V so that the annular gap 118A is inflow communication with an interior 130I of the envelope 38E. A distalend of the push-off tube 120 terminates short of a proximal end of thesleeve 122S of the envelope 38E. However, it is also to be noted, thatthe envelope tube 112E is displaceable relative to the push-off tube 120in the direction of arrow 132A. Instead of the engaging member 128E, thevalve 72V could have a small opening (not shown) in it. The size of theopening in the valve 72V is selected to allow the passage of air, gasand certain other fluids through it in a particular direction ordirections, but is sufficiently small that the viscosity of the fillermaterial will substantially restrict or inhibit the passage of thefiller material through it in a particular directions or directions.

Yet a further way of manipulating the interior 130I of the envelope 38Eis to insert the filler tube 114F into the interior 130I of the envelope38E and to have a slit (not shown) in the filler tube 114F upstream ofthe valve 72V. Thus, if the valve 72V seals about the filler tube 114F,air can still be drawn from the interior 130I of the envelope 38E intothe gap 116P via the slit when the fluid manipulation device isoperated.

A proximal end of the envelope tube 112E carries a connector 134C. Theconnector 134C is a Y-connector having a primary member 136P and asecondary member 138S projecting from the primary member 136P. Theenvelope tube 112E is fast with the primary member 136P of the connector134C. The secondary member 138S of the connector 134C is in flowcommunication with the passage 116P of the envelope tube 112E and,hence, in use with the gap 118A between the envelope tube 112E and thefiller tube 114F. The secondary member 138S is connectable to a fluidmanipulation device (not shown) such as an evacuation pump for creatinga low pressure in the gap 118A and, via the engaging member 128E openingthe valve 72V, the interior 130I of the envelope 38E prior to fillermaterial being charged into the interior 130I of the envelope 38E.

As shown in FIG. 20, the connector 134C includes a retaining mechanism140R for retaining the envelope tube 112E in position relative to theintroducer 22I. The retaining mechanism 140R comprises a receivingformation 142R carried at a proximal end of the introducer 22I. Theretaining mechanism 140R further includes a clip portion 144 forming thedistal end of the connector 134C which clips into the receivingformation 142R to retain the envelope tube 112E in position relative tothe introducer 22I.

A proximal end of the push-off tube 120 carries a gripping formation 146which is accessible externally of the retaining mechanism 140R forenabling the push-off tube 120 to be held while the envelope tube 112Eis moved in the direction of the arrow 132A after charging of theenvelope 38E with the filler material.

As best seen in FIGS. 18 and 19, the equipment 110E may further includea dispensing device 148 for dispensing filler material. The dispensingdevice 148 includes a dispenser 150 feeding into a mixing device in theform of a static mixer 152. A distal end of the static mixer 152 carriesthe filler tube 114F. A Luer lock arrangement 154 is arranged at thedistal end of the static mixer 152 and connects the dispensingarrangement 148 to the connector 134C.

In certain embodiments, the filler material is of a silicone rubber. Toinhibit curing of the filler material prior to its being charged intothe envelope 38E, the filler material is retained in two, separateparts. Thus, the dispenser 150 includes two reservoirs 156 in each ofwhich a part of the filler material is initially received. Eachreservoir 156 has a plunger 158 associated with it for dispensing theparts from the reservoirs 156 into the static mixer 152 where the partsare mixed prior to being charged into the envelope 38E. It is to benoted that the plungers 158 are displaceable together with each othervia a suitable displacing device (not shown) such as a pneumatic gun.

Thus, in use, the filler material to be charged into the envelope 38E isprovided in the dispensing arrangement 148. The dispensing arrangement148 is connected to the connector 134C via the Luer lock 154. Anenvelope 38E, in a deflated condition, is mounted on the envelope tube112E. After the nucleotomy has been performed on the disc 10D, theenvelope tube 112E with the envelope 38E on its distal end is insertedthrough the introducer 22I so that the envelope 38E, in its deflatedcondition, is received within the cavity 36C of the disc 10D. The fillertube 114F is inserted into the interior of the envelope tube 112E sothat the engaging member 128E engages the valve 72V and opens the valve72V. By opening the valve 72V, the interior 130I of the envelope 38E isplaced in fluid communication with the gap 118A between the tube 112Eand the filler tube 114F.

A fluid manipulation device (not shown) is attached to the secondarymember 138S of the connector 134C and the pressure is reduced creating alower pressure within the gap 118A and the interior 130I of the envelope38E and inhibits the formation of gas bubbles in the prosthesis 100P asthe filler material is charged into the envelope 38E.

The filler material is dispensed from the dispensing device 148 into thefiller tube 114F and into the interior 130I of the envelope 38E. Thiscauses the envelope 38E to expand elastically to conform to the shape ofthe cavity 36C of the disc 10D with the envelope 38E being retainedunder tension by the filler material.

After charging of the filler material into the interior 130 of theenvelope 38E, the filler tube 114F is withdrawn. The withdrawal of thefiller tube 114F, causes withdrawal of the engaging member 128E allowingthe valve 72V to close to inhibit leakage of filler material from theinterior 130I of the envelope 38E.

Either before, during or after curing, the envelope tube 112E is movedrelative to the push off tube 120 in the direction of the arrow 132A byholding the push off tube 120 using the gripping device 146. This urgesthe sleeve 122S of the envelope 38E off the end of the envelope tube112E as the envelope tube 112E is withdrawn relative to the push offtube 120. The valve 72V occludes the opening to the envelope 38E. Theequipment 110E, including the introducer 22I, is then withdrawn from thepatient's body, allowing the aperture 30A to occlude as the fibres ofthe annulus fibrosis 16A close over and the procedure is complete.

FIGS. 22 to 24, illustrate further embodiments of equipment for forminga tissue prosthesis, in situ, at a site in a patient's body isillustrated. The equipment 110E includes a stiffening element in theform of a stiffening rod or tube 160S. Prior to insertion of the fillertube 114F into the envelope tube 112E, the stiffening rod 160S isinserted into the passage 116P of the envelope tube 112E. A distal end162 of the stiffening rod 160S projects beyond a distal end of theenvelope tube 112E and terminates at a distal wall in the interior 130Iof the envelope 38E. A gap 161 is created between the envelope tube 112Eand the stiffening rod 160S. The gap 161 and the interior 130I of theenvelope 38E are manipulated by operation of the manipulation device tocause the envelope 38E to collapse on to the distal end 162 of thestiffening rod 160S. This facilitates insertion of the envelope 38E intothe introducer 22I and into the cavity 36C of the disc 10D.

Once the envelope 38E has been located within the cavity 36C, the fluidmanipulation device is turned off to release the envelope 38E from thedistal end 162 of the stiffening rod 160S and this allows the stiffeningrod 160S to be withdrawn. The filler t tube 114F can then be insertedinto the envelope tube 112E, as described above, to enable fillermaterial 60F to be charged into the envelope 38E.

In certain embodiments (not illustrated), the stiffening rod 160S isdimensioned to fit in the interior of the filler tube 114F. With thisarrangement, the gap 118A between the envelope tube 112E and the fillertube 114F is manipulated, as described above, with the stiffening rod160S projecting through the distal end of the envelope tube 112E and theenvelope 38E being collapsed over the distal end 162 of the stiffeningrod 160S.

A proximal end 164 of the stiffening rod carries a cap connector 166which connects to the Y connector 134C to retain the stiffening rod 160Sin position relative to the envelope tube 112E and/or the filler tube114F, as the case may be. The cap connector 166 seals against a proximalend of the Y connector 134C to enable the fluid and or the fluidpressure in the gap 161 and the interior 130I of the envelope 38E to bemanipulated through operation of the withdrawal device, connected to theY connector 134C (the port, which does not have the cap connector 166attached to it). Such a withdrawal device may be a syringe.

In additional exemplary embodiments, there may be provided a prosthesisdelivery system which includes a plurality of nested tubes, an outermosttube of which functions as a cannula in which the remaining tubes arereceived, the remaining tubes forming part of a prosthesis deliveryapparatus, a wall portion of at least one of the tubes having a changein diameter along its length to mate with a corresponding part of adispensing arrangement for use with the prosthesis delivery apparatus.

The prosthesis delivery devices may include a carrier tube which carriesa component of the prosthesis on its distal end and a filler tubereceived in the carrier tube for charging a filler material into thecomponent when the component is located at the desired location at asite in a patient's body. The prosthesis delivery apparatus may includea connector for connection to a withdrawal device to enable gas to bewithdrawn from the component during formation of the prosthesis in situ,the connector being arranged, in use, at a proximal end of theprosthesis delivery apparatus. Further, the prosthesis deliveryapparatus may include a displacement device for displacing the componentof the prosthesis after it has been charged with the filler material.The displacement device may be a further tube mounted about the carriertube. In addition, the prosthesis delivery apparatus may include a covertube to cover the component of the prosthesis, the cover tube fittingover the carrier tube. The cover tube may include a resiliently flexibledistal portion to accommodate the component of the prosthesis. Incertain embodiments, the prosthesis delivery apparatus may include aconnector for connection to a withdrawal device to enable gas to bewithdrawn, or manipulated from at least the component during formationof the prosthesis in situ. More specifically and preferably, thewithdrawal device may manipulate the fluid and or fluid pressure atleast within the delivery apparatus and or the envelope; when in use.Although the fluid and or the fluid pressure manipulation remains activewhilst the filler material is being charged down the filler tube, oncethe material reaches the distal end of the filler tube (i.e., Theproximal end of the component/envelope), the annular space/gap betweenthe filler tube and the carrier tube is occluded by the filler material.Hence during the formation and filling of the envelope, the fluid and orfluid pressure manipulation of at least the interior of the envelope isno longer active.

In certain embodiments, a wall portion of each of the tubes may have achange in diameter along its length. The change in diameter along thelength of each tube may be provided by a flared wall portion of eachtube.

The disclosed systems may include a manipulating arrangement carried ata proximal end of at least the cannula for effecting manipulation of thenested tubes. The manipulating arrangement of the cannula may include arupturing mechanism for rupturing the cannula for removal. The rupturingmechanism may include a plurality of circumferentially spaced,longitudinally extending zones of weakness in a wall of the tube of thecannula and a gripping device arranged at a proximal end of the tube ofthe cannula. The gripping device may comprise a plurality ofcircumferentially spaced radially outwardly extending tabs which arepulled outwardly to cause rupturing of the zones of weakness of thecannula to facilitate withdrawal of the cannula after placement andsetting of the prosthesis.

The systems may include the dispensing mechanism, the dispensingmechanism including a tubuldar element having a distal end whichcorresponds with and mates with that part of the wall portion of the atleast one tube having the change in diameter. The nested tubes may beconfigured to extend proximally of the distal end of the element tooverlie the element. With this arrangement, the length of theunsupported ends of the tubes is considerably shortened therebyimproving the rigidity of the tubes and the stability of the system. Inaddition, the balance of the system is improved rendering it easier forthe clinician to control system.

The dispensing mechanism may include a dispenser to which the element isattachable. The element may be a static mixer.

In certain embodiments, there are provided systems which includes aplurality of tubes, wherein an outermost tube functions as a cannula inwhich the remaining tubes are received, the remaining tubes forming partof a prosthesis delivery apparatus, a wall portion of at least one ofthe tubes having a change in diameter along its length to mate with acorresponding part of a dispensing arrangement for use with theprosthesis delivery apparatus.

In certain embodiments, the prosthesis delivery devices may include atleast one carrier tube which may carry at least one component of theprosthesis on its distal end and at least one filler tube received inthe carrier tube for charging a filler material into the component whenthe component is located at the desired location. The prosthesisdelivery apparatus may include a connector for connection to awithdrawal device to enable gas and or certain fluids to be withdrawnfrom the component during formation of the prosthesis in situ, theconnector being arranged, in use, at a proximal end of the prosthesisdelivery apparatus.

In certain embodiments, the prosthesis delivery apparatus may include adisplacement device for displacing the component of the prosthesis afterit has been charged with the filler material. The displacement devicemay be a further tube mounted about the carrier tube.

In certain embodiments, the prosthesis delivery apparatus may include atleast one cover tube to cover the component of the prosthesis, the atleast one cover tube fitting over the at least one carrier tube. The atleast one cover tube may include a resiliently flexible distal portionto accommodate the component of the prosthesis.

In certain embodiments, a wall portion of each of the tubes has a changein diameter along its length. In some aspects, the change in diameteralong the length of each tube may be provided by a flared wall portionof each tube.

In certain embodiments, the system may include a manipulatingarrangement for effecting manipulation of the tubes located within thecannula. The manipulating arrangement may include a rupturing mechanismfor rupturing the cannula for removal. The rupturing mechanism mayinclude a plurality of spaced zones of weakness in a wall of the tube ofthe cannula and a gripping device arranged at a proximal end of the tubeof the cannula. The gripping device may comprise a plurality ofoutwardly extending tabs which are pulled outwardly to cause rupturingof the zones of weakness of the cannula to facilitate withdrawal of thecannula after placement and setting of the prosthesis.

In certain embodiments, the system may include the dispensing mechanism,the dispensing mechanism including a tubular element having a distal endwhich corresponds with and mates with that part of the wall portion ofthe at least one tube having the change in diameter. The nested tubesmay be configured to extend proximally of the distal end of the elementto overlie the element. With this arrangement, the length of theunsupported ends of the tubes is shortened thereby improving therigidity of the tubes and the stability of the system. In addition, thebalance of the system is improved rendering it easier for the clinicianto control system.

In certain embodiments, the dispensing mechanism may include a dispenserto which the element is attachable and/or the element may be a staticmixer.

In certain exemplary embodiments, there may be provided a prosthesisdelivery system which includes a plurality of nested tubes, one tubebeing a carrier tube which carries at least a component of a prosthesisat its distal end and another tube constituting a delivery tube fordelivering the nested tubes to a site at a patient's body; and a covertube forming part of the nested tubes, the cover tube being arrangedoutwardly of the carrier tube to cover the component when the carriertube is inserted into the delivery tube to protect the component. Thecover tube may have a length approximating a length of the delivery tubewith the carrier tube being dimensioned so that the component protrudesbeyond a distal end of the delivery tube in an uncovered condition.

In certain exemplary embodiments, the system may include a displacementdevice arranged outwardly of the carrier tube with the cover tube beingarranged outwardly of the displacement device. The displacement devicemay be a further tube mounted about the carrier tube. The cover tube mayhave a resiliently flexible distal end to accommodate the component ofthe prosthesis. The resilient flexibility of the distal end of the covertube may be affected and effected by slotting the distal end to providea plurality of leaves able to flex radially outwardly.

The equipment may include at least one sensing arrangement configured tosense a parameter of the filler material charged into the at least oneenvelope. The at least one sensing arrangement may comprise a pressuresensor for sensing the pressure of filler material charged into the atleast one envelope, a temperature sensor for sensing the temperature ofthe filler material charged into the at least one envelope, beconfigured to sense the quantity of filler material charged into theenvelope and/or comprise a flow rate sensor for sensing the rate of flowof the filler material into the at least one envelope. Further, the atleast one sensing arrangement may be configured to sense the presence ofgas bubbles in the filler material charged into the at least oneenvelope. Further, the sensing arrangement may be configured to sensethe displacement of the pistons of the dispenser mechanism. Further, thesensing arrangement may be configured to sense the force applied to thepistons to displace the pistons of the dispenser mechanism.

In certain embodiments, there may be provided equipment for forming atissue prosthesis in situ at a site in a patient's body, the equipmentcomprising a tubular delivery device, the delivery device defining apassageway, and at least one envelope of the prosthesis being mountableto a distal end of the delivery device to be received in a cavity at thesite; a stiffening element arranged to project from a distal end of thedelivery device with the envelope, in use, being received over thestiffening element to be supported by the stiffening element; and aremoval mechanism carried by the delivery device for enabling the atleast one envelope to be removed from the delivery device after the atleast one envelope has been charged with filler material via the fillermember.

In certain embodiments, the stiffening element may be an elongateelement, such as a rod or tube, receivable with clearance in thepassageway of the delivery device to define a gap to enable at leastsome fluid to be withdrawn from the at least one envelope to collapsethe envelope on to a distal end of the elongate element projecting fromthe distal end of the delivery device.

The equipment may include a filler member receivable in the passagewayof the delivery device after removal of the stiffening element, thefiller member being receivable, after removal of the stiffening element,with clearance in the passageway to define a gap to enable fluid to bemanipulated at least from the at least one envelope.

In certain embodiments, the equipment may include a tubular fillermember receivable in the passageway of the delivery device, the fillermember being receivable with clearance in the passageway to define a gapto enable fluid to be manipulated at least from the envelope and thestiffening element being an elongate element receivable through thepassage of the filler member.

In certain embodiments, there may be provided a tissue prosthesisinsertion system which includes a first assembly comprising a pluralityof nested tubes, one of the tubes being a carrier tube which, in use,receives a component of a tissue prosthesis at a distal end of thecarrier tube; a magnetic mount carried at a proximal end of the firstassembly; a second assembly removably attachable to the first assembly;and an attachment device carried at a distal end of the second assembly,the attachment device being responsive to the magnetic mount of thefirst assembly, the magnetic mount and the attachment device carryingcomplementary engaging formations to facilitate sealing between themagnetic mount and the attachment device.

The use of a plurality of nested tubes, as described herein, may haveseveral advantages. For example, the device may be more compact thanother devices which allow the device and all of its components to fitinto a smaller confinement. This may, in certain embodiments, provide ameans for conducting percutaneous and/or minimally invasive procedures.The nested tubes also reduce trauma to the tissue that can result fromrepeatedly moving instruments in and out of the body. The nested tubesalso provide additional protection for the instruments inside of theoutermost tube. Additionally, the device can be more easily maintainedin its desired location and the system may operate with less frictionalresistance. Since the working cannula is fixed and docked relative tothe patient, and all the other nested tubes lock to the working cannula,the positioning and deployment of the envelope within the disc space isconsistent and repeatable. Also, since all the tubes are fixed relativeto each other, during any process of the implant procedure, the risk ofdamage to the envelope is minimised because movement (laterally and oraxially) of the envelope is minimised. Excessive movement of theenvelope during any part of the implant procedure increases its chancesof being damaged by either the surrounding tissue or other tubes (inparticular the working cannula).

The complementary engaging formations of the magnetic mount and theattachment device may comprise a Luer slip fitting (see, e.g., the luerslip fitting mechanism 1006 of FIG. 94). By “Luer slip fitting” is meantthat one of the engaging formations comprises a tapered socket and theother of the engaging formations comprises a tapered fitting receivablein the tapered socket to form a sufficient or substantial seal betweenthe fitting and the socket.

In certain embodiments, instead of a luer slip fit formation, sealingcan be achieved through the use of an O-ring or a gasket between thesurfaces of the mounts such that a substantial seal is formed.

Also, one engaging end can have a protruding member, in the form of atapered fitting, and the receiving end may comprise an engagingformation (not necessarily tapered) which is substantially parallel, butof a softer material than the protruding member such that it deforms toaccommodate the protruding member and form a seal. Two surfaces ofdissimilar materials (dissimilar hardness) engaging with mechanicalinterference may provide a substantial seal. For two surfaces of similarmaterials engaging with mechanical interference, to improve the seal, adissimilar material (e.g. Silicone) can be used between the two surfacesto provide a substantial seal. Also the applicant of a sealant betweenthe two similar surfaces can provide the necessary seal. FIG. 92illustrates the use of an O-ring 1000 between the two surfaces. Althoughnot illustrated, the seal could also be formed at the interface 1002 ofthe two surfaces.

The magnetic mount of the first assembly may be a first magnetic mountand the attachment device may comprise a second magnetic mount whichmagnetically attaches to the first magnetic mount.

In certain embodiments, both mounts do not necessarily have to bemagnetic, as long as one is magnetic, the other can be of a materialwhich is attracted to a magnet.

Alternatively, another means of engaging two surfaces is through theapplication of an adhesive on one or more of the surfaces and using thetackiness of the surfaces as a means for engaging the two surfaces.

Other means of coupling can include a luer lock connection (see, e.g.,the luer locking mechanism 1004 of FIG. 93), bayonet connection, ballseal connection and any other connection which allow the two engagingcomponents to be reversibly attachable. To achieve the closed systemstatus, any of the listed engaging means can be used in conjunction withany or all of the above mentioned sealing mechanisms either singly or incombination.

The second assembly may include a stiffening member received within thefirst assembly, the stiffening member, in use, projecting into aninterior of the component of the prosthesis, the stiffening memberhaving a securing formation at its proximal end which engages theengaging formation of the magnetic mount in a sealing manner.

Further, the system may include a withdrawing device attachable to thefirst assembly, the withdrawing device, in use, being in communicationwith the interior of the component of the prosthesis and, with thestiffening member in position, creating a closed system, containedsystem, or hermetically sealed system so that operating the withdrawingdevice causes an increase in the volume of the closed system with acorresponding reduction in the pressure in the interior of thecomponent, resulting in the component collapsing about the stiffeningmember.

The withdrawing device may be operable to test the integrity of thefirst assembly with the component mounted on the first assembly.

The first assembly may include a protective sheath, constituting one ofthe tubes of the first assembly, received over the component after ithas been collapsed on to the stiffening member. At least one of theprotective sheath and the component may be treated to facilitate slidingdisplacement between the protective sheath and the component. Thetreating of the protective sheath and/or the component may occur priorto inserting the first assembly into a working cannula used forinsertion of the tissue prosthesis into position at a site in apatient's body. The treating may involve immersing the distal end of thefirst assembly in a lubricating fluid such as water. Instead, thetreating may involve coating an inner surface of the protective sheathwith a hygroscopic material or a hydrophilic material such as, forexample, a hydrogel. Alternatively, rather than treating the innersurface of the protective sheath, the protective sheath itself may bemade from lubricious materials which include, but not limited to,polytetrafluoroethylene (Teflon), acetal, polypropylene, polyethylene.All of the above mentioned materials may also be a treatment option forthe inner lining of the protective sheath. Further, should theprotective sheath be made from the described polymers, they may also betreated to improve the lubricity.

The protective sheath may have a distal end configured to facilitatesliding displacement of the protective sheath relative to the componentof the prosthesis. In some aspects, the distal end of the protectivesheath may be configured by being bifurcated. The protective sheath mayinclude an operating member arranged at its proximal end to facilitatemanipulation of the protective sheath.

The systems may include the component, the component comprising at leastone envelope of an elastically deformable material, the at least oneenvelope defining an access opening with a flow control member beingarranged in the access opening, the flow control member being configuredto permit withdrawal of fluid from an interior of the at least oneenvelope prior to filling the at least one envelope with a fillermaterial. The flow control member may be a flow control valve which, ina rest condition, defines a withdrawal opening to allow withdrawal ofthe fluid from the interior of the at least one envelope. In certainaspects, the valve may be a duckbill valve having a pair of opposedoperating flaps, the flaps being shaped so that, in their restcondition, they are spaced from each other to define the withdrawalopening The flaps may be skewed or staggered so that when the flaps cometogether, a small opening is defined. Other types of valves includeumbrella valves, star valves, valves which have at least 1 flap(preferably 2), ball valve, dome shaped (e.g., umbrella shaped) valvewith a slit(s) cut into the very tip of the dome. For example, FIGS. 87and 88 illustrate an exemplary ball valve in an open and closedposition, respectively and FIGS. 89 and 90 illustrate an exemplaryumbrella valve in an open and closed position, respectively. The valvemay be pressure sensitive whereby it prevents flow in a particulardirection at a certain pressure. When that certain pressure is exceeded,it allows for fluid to flow in that particular direction.

In certain embodiments, the flow control member may not necessarily haveto be a valve. If the neck of the envelope were inverted, once theenvelope has been filled, the inverted neck would form a flap whichseals to prevent the backflow of material. The inverted neck may beparallel (tubular), tapered or stepped (i.e., the diameter changes).Also, another alternative to a valve (which is built into the envelope)is a tubular section which has a gradual reduction in diameter (See, forexample, FIG. 91). This functions like a valve but may not necessarilybe referred to as a valve. Various cross sections are possible for thisform of flow restricting mechanism. It still has an opening in itsrelaxed state but once the envelope is filled, the significantly moreviscous biomaterial cannot flow back out. All of the above mentioneddesign features can be applicable for a valve or a valve like structurewhich does not have an opening defined in its relaxed state. It couldrequire an extending member (either an extension of the carrier tube orother) to open up the valvular member in order to define this opening,which may be necessary to operate the envelope (e.g., collapse).Alternate to a valve, the delivery apparatus can be twisted (or rotated)once the filling is completed and this twisting crimps and seals theneck of the implant.

In certain embodiments, the flow control member in its resting conditionmay be configured to define at least one withdrawal opening and in itsnon resting condition may be configured to allow less viscous fluids toflow in at least two directions and more viscous fluids to flow in atleast one direction. Less viscous materials are those materials thatrequire less energy to flow. Less viscous fluids include, but notlimited to, air, water, certain oils. (The term “less viscous” can beseen as a relative term where it defines a material which is lessviscous than the material being introduced into the envelope as thebiomaterial, or less viscous than the material which is limited to flowin at least one direction by the flow control member.)

In certain embodiments, the flow control member in its first conditionmay be configured to define at least one withdrawal opening and in itssecond condition may be configured to allow less viscous fluids to flowin at least two directions and more viscous fluids to flow in onedirection.

In some aspects, other flow control mechanisms or means for flow controlmay be used. For example star valves, multi cuspid valves, umbrellavalves. In some aspects, other flow control mechanisms may be used aslong as that mechanism controls the flow of certain fluids in at leastone direction. In certain aspects, the flow control mechanism may beconfigured to allow less viscous fluids to flow in at least twodirections and more viscous fluids to flow in at least one direction.For example, using certain flow control mechanisms fluids such as gas,water, solutions or combinations thereof, will be permitted tosubstantially flow in at least two directions through the flow controlmechanism and viscous filler material will be permitted to substantiallyflow through the control mechanism into the envelope.

In certain aspects, the means for flow control may be configured toallow less viscous fluids to flow in either direction or more viscousfluids to flow in at least one direction.

In certain embodiments, the flow control member may be configured toallow less viscous filler material to flow into the envelope where thefiller material becomes more viscous, thereby preventing it from flowingback through the flow control member.

One advantage of certain flow control members disclosed herein is thatthey may be configured to permit viscous materials to flow in onedirection allowing the carrier tube to be detached after the viscousmaterial has been delivered to the envelope. Thus permitting shortersurgery times and anaesthesia for the patient, resulting in a fasterrecovery and less chance of complications.

The second assembly may comprise a filler tube received through thefirst assembly to communicate with the interior of the envelope and afiller material dispenser mountable to a proximal end of the fillertube. The dispenser assembly may feed into a static mixer, a distal endof the static mixer carrying the attachment device, the arrangementbeing such that, when the second assembly is fast with the firstassembly and the withdrawing device is attached to the first assembly, asecond closed system is created which enables fluid to be withdrawn fromthe interior of the envelope by the withdrawing device to create a lowpressure region in the envelope. A “low” pressure may be defined as apressure below ambient pressure.

Whether the filler material is a single part, two part, etc, it can bepremixed and delivered through the filler tube rather than having to gothrough a static mixer. Alternatively, the mixing can be through adynamic mixer. Also, the in situ curing filler material usually relieson a catalyst and or cross-linker. That molecule required to initiatethe chemical reaction can be added into the mixture by having it coatedon the surfaces the filler material is in contact with. This includesbut is not limited to, the static mixer, inner lining or filler tube,inner lining of envelope etc.

The dispenser may contain filler material, the filler materialpreferably being of the same class or type of material as the materialof the envelope so that, when the envelope has been charged with thefiller material and the filler material has been allowed to set, atissue prosthesis is formed which is elastically deformable. Theenvelope is filled with the filler material initially up until theenvelope reaches its relaxed configuration (i.e., its premolded form).Then, when the filling continues, it undergoes elastic deformation forup to 10 times its relaxed volume, or for up to 3, 4, 5, 6, 7, 8, or 9times its relaxed volume or until it fills to conform substantially tothe cavity of the nucleus where the substantiality of the fill is notlimited by the limitations of the apparatus.

In certain embodiments, the envelope may be resilient and elasticallydeformable. The in situ curing material may also be resilient andelastically deformable. When the systems combine, they form a resilientand elastically deformable implant. When the envelope and in situmaterial combine, they take on the properties substantially similar tothat of the envelope, or to that of the in situ curing material, or thecombined system may take on completely different mechanical properties(possibly due to the fact that when they combine, they undergo achemical reaction which changed the properties altogether). By“elastically deformable” it is meant that the prosthesis can be deformedby the application of a force and, upon removal of the force, the tissueprosthesis substantially returns to its undeformed state. In certainembodiments, the filler material may be of a different class or typethan the material of the envelope. For example, but not limited to, apolyurethane envelope filled with a silicone filler material, a siliconeenvelope with a polyurethane filler material, a polyester envelopefilled with a silicone filler, polyester envelope filled withpolyurethane, or other combinations of acceptable filler material andacceptable envelope material. Further, the envelope may be apolyethylene envelope filled with either a polyurethane or a siliconefiller. Combinations of the materials also apply. For example, thefiller may be a combination of silicone and polyurethane.

The system may include an obturating device receivable in one of thetubes of the first assembly for tamping a part of the tissue prosthesisinto position after formation of the tissue prosthesis. The obturatingdevice may carry a locking member at its proximal end for locking to aworking cannula of the system so that, after tamping of the part of thetissue prosthesis, the working cannula and the obturator can be removedsimultaneously.

In certain embodiments, there may be provided a tissue prosthesisinsertion system which includes an assembly comprising a plurality ofnested tubes, one of which is a carrier tube for carrying a component ofa tissue prosthesis at its distal end and another of which is a fillertube received with clearance in the carrier tube to define a passagebetween the filler tube and the carrier tube, the proximal end of thefiller tube and the proximal end of the carrier tube being in sealingengagement; and a withdrawing device attachable to the assembly so that,when the withdrawing device is attached and the component of the tissueprosthesis is mounted on the distal end of the carrier tube, a closedsystem is formed which allows the withdrawing device to be used toincrease the volume of the closed system to form a low pressure regionat least in the component.

The assembly may comprise a stiffening member received in the carriertube, a proximal end of the stiffening member and a proximal end of theassembly carrying complementary engaging formations for enabling thestiffening member to engage sealingly with at least one of the pluralityof nested tubes to create an initial closed system, operation of thewithdrawing device forming a low pressure region in the interior of thecomponent, in use, to cause the component to collapse around thestiffening member. The system may include a filler tube insertable intothe carrier tube after removal of the stiffening member to contribute tothe formation of a further closed system which is then acted on by thewithdrawing device to increase the volume of the closed system to reducethe pressure in the interior of the component.

The withdrawing device may be operable to test the integrity of thesystem to ensure that there are no leaks in the system.

In certain embodiments, there may be provided a tissue prosthesisinsertion system which includes a working cannula for accessing a sitein a patient's body percutaneously and/or minimally invasive manner forcarrying out a tissue prosthesis insertion procedure at the site; and anobturating device receivable in the cannula for tamping a part of atissue prosthesis into position after formation of the tissueprosthesis.

The obturating device may comprise a blunt-ended rod slidably receivablein the working cannula.

In certain embodiments, there may be provided a tissue prosthesiscomponent which includes an envelope of an elastically deformablematerial, the envelope defining an access opening; and a flow controlmember arranged in the access opening, the flow control member beingconfigured to permit withdrawal of fluid from an interior of theenvelope prior to filling the envelope with a filler material.

The flow control member may be a flow control valve which, in a restcondition, defines a withdrawal opening to allow the passage of certainfluids in both directions. The envelope may have a neck portion, theneck portion defining the access opening and the flow control memberbeing arranged within the neck portion.

In certain embodiments, there may be provided methods of preparing afirst assembly of a tissue prosthesis system for insertion into apatient's body, the methods comprising providing the first assemblywhich comprises a plurality of nested tubes, one of the tubes being acarrier tube; mounting a component of the prosthesis on a distal end ofthe carrier tube, the component being of an elastically deformablematerial; inserting a stiffening member into the first assembly so thatthe stiffening member extends into an interior of the component andcausing a proximal end of the stiffening member to sealingly engage aproximal end of the first assembly; attaching a withdrawing device tothe first assembly so that the withdrawing device is in fluidcommunication with the interior of the component; and operating thewithdrawing device to reduce the pressure in the interior of thecomponent to cause the component to collapse about the stiffeningmember.

The methods may include attaching the withdrawing device to a fluid portof the first assembly in a sealing manner. The withdrawing device may bea syringe which is attached by a Luer lock mechanism to the fluid portof the first assembly.

After the component has been collapsed about the stiffening member, themethods may include placing a protective sheath about the component.More particularly, the methods may include placing the protective sheathabout the component by sliding the protective sheath over the component,the protective sheath constituting one of the tubes of the nested tubesof the first assembly. Further, the methods may include treating one ofthe protective sheath and the component with a lubricating medium tofacilitate relative displacement between the protective sheath and thecomponent.

The methods may include using the withdrawing device to test theintegrity of the combination of the first assembly and the component andthe stiffening member attached to the first assembly.

In certain embodiments, there may be provided methods of forming atissue prosthesis at a site in a patient's body, the methods includingproviding a first assembly comprising a plurality of nested tubes, oneof the tubes being a carrier tube with a component of the prosthesiscarried at a distal end of the carrier tube; inserting the firstassembly into a cannula placed in the patient's body; magneticallyattaching a second assembly to a proximal end of the first assembly; andcharging a filler material from the second assembly into the componentand allowing the filler material to set.

The methods may include, initially, preparing the first assembly asdescribed above.

The methods may include, once the distal end of the first assembly is atthe desired location at the site in the patient's body, withdrawing theprotective sheath to expose the component, the component being anenvelope of an elastically deformable material. Further, the methods mayinclude using the withdrawing device to test the integrity of the firstassembly either after or before withdrawing the protective sheath.

The methods may include removing the stiffening rod prior tomagnetically attaching the second assembly to the first assembly.Further, the methods may include causing the second assembly to engagesealingly with the first assembly so that, together with the componentand the withdrawing device, a closed system is formed.

After the second assembly has been attached to the first assembly, themethods may include operating the withdrawing device to create a lowpressure in the component. Further, the methods may include using thewithdrawing device to test the integrity of the system comprising thetwo assemblies and the component attached to the first assembly.

The methods may include dispensing the filler material from a dispenserof the second assembly. Preferably, the methods include purging fillermaterial from the dispenser prior to attaching the dispenser to a staticmixer constituting a part of the second assembly. The methods mayinclude, during filling of the component via a filler tube extendingfrom the static mixer, operating the withdrawing device at least tomaintain, or increase, the volume of the closed system.

The methods may include after filling the component, detaching thecarrier tube from the tissue prosthesis formed by the combination of thecomponent and the filler material contained in the component. Thecarrier tube may be detached prior to the filler material having curedor set or after the filler material has at least partially set. Themethods may include detaching the carrier tube from the tissueprosthesis when the required pressure has been reached in the component.In the case of intervertebral disc nucleus prosthesis, the requiredpressure may be that which inhibits distraction of the disc.

In certain embodiments, the methods may include detaching the tissueprosthesis by relative axial motion between the carrier tube and adisplacement device of the first assembly. The displacement device maybe a further tube arranged about the carrier tube and the relative axialmotion may be effected and affected by withdrawing the carrier tuberelative to the displacement device. In other embodiments, the methodsmay include detaching the tissue prosthesis by filling the componentwith filler material to the extent that the component is released fromthe carrier tube. In further embodiments, the methods may includedetaching the tissue prosthesis by manipulating the carrier tuberelative to the component to cause separation of a part of the componentattached to the carrier tube from a remainder of the component, theseparation occurring at a zone of weakness in the component. Themanipulation may involve rotating the carrier tube with respect to thecomponent.

The methods may include, after formation of the tissue prosthesis,tamping a part of the tissue prosthesis into position. If necessary ordesirable, the methods may include, before placing the component inposition at the site, preparing the site. The methods may includepreparing the site by removing degenerative tissue from the site priorto placing the component at the site.

In certain embodiments, there may be provided equipment for forming atissue prosthesis in situ at a site in a patient's body, the equipmentcomprising a delivery device displaceably receivable in a lumen of anintroducer, the delivery device defining a passageway; an envelopecarried at a distal end of the delivery device, the envelope being of abiologically inert, elastically deformable material capable of beingexpanded to conform to an interior surface of a cavity formed at thesite; and a supply of a filler material chargeable in a fluent stateinto the envelope through the passageway of the delivery device, thefiller material being of the same class of material as the envelope toform, when cured, together with the envelope, a unified prosthesis.

The equipment may include an aperture forming element to form anaperture into the site, the aperture forming element being receivablethrough the introducer for delivery to the site. The aperture formingelement may, for example, be a trocar.

Further, the equipment may include a tissue removal mechanism insertablethrough the aperture for removing tissue, if required, to form thecavity. The tissue removal mechanism may comprise mechanical,ultrasonic, laser, Argon gas or radio frequency ablation mechanisms, orthe like in combination with suction and irrigation. For example, thetissue removal mechanism may be a reaming-type tool.

The equipment may include a dispenser containing the supply of fillermaterial. Further, the equipment may include a sensing arrangementconfigured to sense a parameter of the filler material charged into theenvelope. The sensing arrangement may comprise a pressure sensor forsensing the pressure of filler material charged into the envelope, atemperature sensor for sensing the temperature of the filler materialcharged into the envelope, be configured to sense the quantity of fillermaterial charged into the envelope and/or comprise a flow rate sensorfor sensing the rate of flow of the filler material into the envelope.Further, the sensing arrangement may be configured to sense the presenceof air bubbles in the filler material charged into the envelope.

In certain embodiments, there may be provided equipment for forming atissue prosthesis in situ at a site in a patient's body, the equipmentcomprising a tubular delivery device, the delivery device defining apassageway, an envelope of the prosthesis being mountable to a distalend of the delivery device to be received in a cavity at the site; afiller member receivable in the passageway of the delivery device, thefiller member being receivable with clearance in the passageway todefine a gap to enable fluid to be manipulated at least from theenvelope, at least prior to the filler material being charged into theenvelope; and a removal mechanism carried by the delivery device forenabling the envelope to be removed from the delivery device after theenvelope has been charged with filler material via the filler member.

The equipment may include a tubular introducer and an aperture formingelement, such as a trocar, to form an aperture at the site, the apertureforming element being receivable through the introducer for delivery tothe site.

Further, the equipment may include a tissue removal mechanism insertablethrough the aperture for removing tissue, if required, to form thecavity.

The introducer and the delivery device may include a retainingarrangement for retaining the delivery device with respect to theintroducer.

In addition the equipment may include a supply of filler materialattachable to a proximal end of the filler member. The filler materialmay be a mixture of a plurality of parts and the supply of fillermaterial may comprise a dispenser defining a plurality of chambers ineach of which one part of the filler material is received prior to use.The dispenser may further comprise a mixer arranged intermediate anoutlet of the dispenser and the proximal end of the filler member formixing the filler material prior to charging it into the envelope.

A proximal end of the delivery device may carry a connector forconnection to a fluid manipulation mechanism such as an evacuation pump.

The equipment may include the envelope, the envelope being of anelastomeric material capable of expanding to up to about 3, 4, 5, 10,40, 50, 100, or 150 times its relaxed state. Preferably, the envelope isexpanded to be stretched and retained under tension after being chargedwith the filler material. The envelope may include a neck portion, theneck portion defining a zone of weakness for facilitating separation ofthe envelope from the delivery device.

FIGS. 25-32, illustrate an exemplary assembly of a tissue prosthesisinsertion system designated generally by the reference numeral 10FA. Theassembly 10FA comprises a plurality of nested tubes 12N. As shown inFIG. 28, the set of nested tubes 12N comprises an inner, carrier tube14C on which a component, in the form of an envelope 16E of a tissueprosthesis is mounted, the envelope 16E being mounted on a distal end ofthe carrier tube 14C. The carrier tube 14C is received within a push-offtube 18P which is used for removing the envelope 16E, after filling,from the carrier tube 14C as will be described in greater detail below.

The nested tubes 12N further include a protective sheath 20P, arrangedabout the push-off tube 18P. As illustrated in FIGS. 26 and 28, theprotective sheath 20P is of a length to cover the envelope 16E, thesheath 20P projecting beyond a distal end of the envelope 16E when inits operative, protective position. It is to be noted that the nestedtubes 12N are shown, in use, mounted in a working cannula 22C used forinserting the first assembly 10FA percutaneously to deliver the envelope16E into a site at a patient's body in which the prosthesis is to beformed. The nested tubes 12N may be of a metal material such as a steelmaterial which is bio-compatible.

The first assembly 10FA further includes a stiffening member in the formof a stiffening rod 24S. The stiffening rod 24S is of a length toproject from a proximal end of the first assembly 10FA through a lumen26L (FIG. 28) of the carrier tube 14C to be received in an interior 28Iof the envelope 16E.

A collar assembly 30C is arranged at a proximal end of the nested tubes12N. The collar assembly 30C comprises a first collar 32C secured to aproximal end of the cannula 22C. The cannula 22C has a pair ofdiametrically opposed, longitudinally extending slits, one of which isshown at 34SL in FIG. 25 of the drawings, arranged distally of thecollar 32C. The protective sheath 20P is slidably arranged relative tothe cannula 22C and has a pair of opposed, radially outwardly extendingtabs 38T arranged at its proximal end. The tabs 38T project through theslits 34SL in the cannula 22C to enable a clinician to manipulate theprotective sheath 20P.

The push-off tube 18P has a collar 36CO arranged at its proximal end,the collar 36CO being connected to the collar 32C of the cannula 22C viaa bayonet fitting. The carrier tube 14C carries a branch or Y-connector42B at its proximal end, the Y-connector 42B extending from a collar40C. The collar 40C attaches to the collar 36CO of the push-off tube 18.The Y-connector 42B carries a magnetic mount 44M at its proximal end.The magnetic mount 44M carries a plurality of annular magnets 46M. Thesemagnets 46M are rare earth magnets and are covered by a cover member48C.

The Y-connector 42B further includes a branch limb 50B defining aconnection port 52C for a withdrawing device. The connection port 52C isin communication with a passage (not shown) defined between the carriertube 14C and, initially, the stiffening rod 24S. The stiffening rod 24Scarries a securing formation in the form of a mount 54M at its proximalend. A distal part 56D of the mount 54M is tapered and engages a taperedsocket 58S defined by the magnetic mount 44M in a sealing or closingmanner so that, once a withdrawing device has been attached to the port52C, a closed system is formed.

More particularly, once the envelope 16E has been attached to the distalend of the carrier tube 14C, the stiffening rod 24S is inserted throughthe lumen 26L of the carrier tube 14C to be received in the interior 28Iof the envelope 16E. When the distal end of the stiffening rod 24S isreceived in the envelope 16E, the distal part 56D of the mount 54M ofthe stiffening rod 24S sealingly engages with the socket 58S in themagnetic mount 44M of the Y-connector 42B to form a substantial seal, ora hermetic seal.

A withdrawing device in the form of a syringe 62S (FIG. 30) is connectedvia a Luer fitting 64L to the port 52C of the Y-connector 42B to form aclosed system. A plunger 66P of the syringe 62S is drawn in thedirection of arrow 68A. This increases the volume of the closed system,reducing the pressure in the interior 28I of the envelope 16E andcausing the envelope 16E to collapse about the distal end of thestiffening rod 24S.

Prior to insertion into the cannula 22, the tabs of the protectivesheath 20P are gripped by an operator assembling the first assembly 10FAand are urged in the direction of arrow 70A (FIG. 26) to cause theprotective sheath 20P to slide over and protect the envelope 16E. Tofacilitate sliding movement between the protective sheath 20P and theenvelope 16E, a distal end of the first assembly 10FA can be immersed ina suitable lubricating medium such as, for example, water. In thisregard it should be noted that the envelope 16E is made of siliconematerial rendering it hydrophobic. Thus, the water acts as a lubricantand enables the protective sheath 20P to be slid over the envelope 16E.Instead of immersing the distal end of the first assembly 10FA in thelubricating medium, an internal surface of the protective sheath 20Pcould, optionally, be coated with a lubricating medium of a hygroscopicor hydrophilic material such as a hydrogel. Alternatively, rather thantreating the inner surface of the protective sheath, the protectivesheath itself may be made from lubricious materials which include, butnot limited to, polytetrafluoroethylene (Teflon), acetal, polypropylene,polyethylene. All of the above mentioned materials may also be atreatment option for the inner lining of the protective sheath. Further,should the protective sheath be made from the described polymers, theymay also be treated to improve the lubricity.

After retracting the sheath 20P in the direction opposite to that ofarrow 70A, the integrity of the first assembly 10FA is tested for leaksby further withdrawing the plunger 66P of the syringe 62S in thedirection of arrow 68A. If the plunger 66P does not return to itsprevious position, this is an indication that there is a leak in thefirst assembly 10FA and remedial action can be taken to locate the leak.Conversely, should the plunger 66P return to its previous position, thisis an indication that the integrity of the first assembly 10FA is intactand the procedure can proceed.

Instead of pulling on the plunger 66P of the syringe 62S, testing of theintegrity of the first assembly 10FA could involve pushing on theplunger 66P of the syringe 62S and then releasing the plunger 66P. Ifthe plunger 66P does not return to its original position that is anindication that there is a leak in the system such as may occur if theenvelope 16E is torn.

FIGS. 29-32, show a tissue prosthesis insertion system which isdesignated generally by the reference numeral 80S. The system 80Sincludes the first assembly 10FA and a second assembly 82SE. The secondassembly 82SE comprises a filler tube 84F including a static mixer 86Sat a proximal end of the filler tube 84F. The static mixer 86S issecured to a distal end of a filler material dispenser 88F. The fillermaterial dispenser 88F has a screw-threaded attachment 89 for engaging ascrew-threaded boss 90B at a proximal end of the static mixer 86S. Adistal end of the static mixer 86S carries an attachment device in theform of a second magnetic mount 92M. As illustrated in FIG. 31 themagnetic mount 92M comprises a pair of annular rare earth magnets 94Rclosed off by a cover 96C. The mount 92M also includes a tapered fitting98. The tapered fitting 98 of the mount 92M and the tapered socket 58Sof the mount 44M define complementary engaging formations. Thus, thetapered fitting 98 is received within the socket 58S of the magneticmount 44M of the Y-connector 42B in a hermetically sealing manner, thefitting 98 and the socket 58S constituting a Luer slip fitting. Thus,once again, once the syringe 62S has been attached to the port 52C ofthe Y-connector 42B, a closed system is formed.

The benefit of magnetically attaching the second assembly 82SE to thefirst assembly 10FA is that the requirement for relative rotationbetween the two assemblies 10FA and 82SE for attachment to each other isobviated, as would the case be otherwise if were for example a luer lockattachment. This also enables the cannula 22C of the first assembly 10FAmore accurately to be retained in position, in use. It also maintainsthe engagement of the two assemblies 10FA and 82SE during filling of theenvelope 16E. The filler material used for forming the tissue prosthesisis a silicone rubber material. To inhibit curing of the filler materialprior to its being charged into the envelope 16E, the filler material isretained in two, separate parts. For this purpose, the dispenser 88Fincludes two separate reservoirs 100R, in each of which one part of thefiller material is initially received. Each reservoir 100R has a plunger(not shown) associated with it for dispensing the parts of the fillermaterial simultaneously from the reservoirs 100R into the static mixer86S where the parts are mixed prior to being charged into the fillertube 84F to be injected into the interior 28I of the envelope 16E. Theplungers are displaceable together with each other via a suitabledisplacing device (also not shown), for example, a pneumatic gun.

After removal of the stiffening rod 24S, the second assembly 82SE isattached to the first assembly 10FA via the magnetic mounts 44M and 92M.More particularly, the part of the second assembly 82SE comprising thestatic mixer 86S with the filler tube 84F projecting from the staticmixer 86S is magnetically attached to the first assembly 10FA via themagnetic mounts 44M and 92M with the fitting 98 sealingly engaging inthe socket 58S. Prior to attaching the dispenser 88F to the static mixer86S, filler material is purged from the reservoirs 100R by urging theplungers towards the threaded end 89 of the dispenser 88F to expel aportion of filler material from the reservoirs 100R to ensure that thecorrect ratio of the two parts of the filler material is dispensed. Thedispenser 88F is then attached to the static mixer 86S.

The pressure in the interior 28I of the envelope 16E is again lowered bywithdrawing the plunger 66P of the syringe 62S in the direction ofarrows 68A. This serves to collapse the envelope 16E prior to the fillermaterial being charged via the filler tube 84F into the interior 28I ofthe envelope 16E. To enable the pressure in the interior 28I of theenvelope 16E to be lowered, the filler tube 84F is a loose fit withinthe carrier tube 14C to create an annular passage 102P (FIG. 32) viawhich air, gas or certain other fluids can be withdrawn from theinterior 28I of the envelope 16E by the syringe 62S.

After lowering the pressure in the interior of the envelope 16E, theintegrity of the system 80S is again checked by further attempting towithdraw the plunger 66P from the syringe 62S in the direction of thearrows 68A. Should the plunger 66P remain in its withdrawn position,this is an indication that there is a leak in the system and remedialaction can be taken to locate the leak. Conversely, should the plunger66P return to its previous position, this is an indication that theintegrity of the system 80S is intact and the clinician can proceed.Once again, instead of pulling the plunger 66P, testing could involvepushing the plunger 66P and determining whether or not it returns to itsoriginal position. If not, that is an indication that there is a leak inthe system 80S and remedial action can be taken to locate the leak.

Referring generally to FIGS. 33-37, to insert the nucleus prosthesisinto the disc, an incision in made in the patient's skin and anannulotomy is performed on the annulus 126AN of the disc 124D in aminimally invasive manner to form an opening 132AN. This enables accessto be gained to the interior of the disc 124D. To perform theannulotomy, the cannula 22C is inserted through the incision until adistal ends abuts the annulus 126AN. An annulotomy performing tool, suchas a trocar or a guide wire plus dilator (not shown), is insertedthrough the cannula 22C and pierces the annulus 126AN to enable accessto be gained to the nuclear material of the disc 124D. If necessary, anucleotomy is performed to remove the nuclear material. However, incertain circumstances, the degenerative process may have dehydrated,extruded or shrunken the nuclear material so that a cavity has alreadybeen formed and the necessity to perform the nucleotomy is obviated.

Whether or not a nucleotomy is performed, once the cavity in the disc124D is present, the first assembly 10FA is inserted into the cannula22C. As indicated above, the first assembly 10FA comprises the carriertube 14C with the envelope 16E mounted on a distal end of the carriertube 14C, the push-off tube 18P and the protective sheath 20P, with theprotective sheath 20P extending over the envelope 16E.

Once the envelope 16E is in position within the disc 124D, theprotective sheath 20P is withdrawn by urging the tabs 38T of theprotective sheath 20P in the direction opposite to that of the arrow70A, the tabs 38T being received within recesses 104R of the collar 32Cof the cannula 22C.

The first assembly 10FA is locked in position relative to the workingcannula 22C by the bayonet fitting of the collar 36CO of the push-offtube 18P engaging the collar 32C of the cannula 22C.

The stiffening rod 24S is removed and the second assembly 82SE isattached to the first assembly 10FA, as previously described. Somefiller material is purged from the reservoirs 100R of the dispenser 88Fand the dispenser 88F is then attached to the proximal end of the staticmixer 86S. This re-forms the closed system enabling air to be removedfrom the envelope 16E by operating the syringe 62S and pulling itsplunger 66P in the direction of arrows 68A.

The plungers of the dispenser 88F are then urged towards the distal endof the dispenser 88F to discharge material from the reservoirs 100R. Theparts of the filler material discharged from the reservoir 100R aremixed together in the static mixer 86S before being fed into the fillertube 84F. The plunger 66P of the syringe 62S is continued to bewithdrawn in the direction of arrow 68A during passage of the fillermaterial along the filler tube 84F at least to maintain or to increasethe volume of the closed system to remove air from the envelope 16E asthe filler material is charged into the envelope 16E. The fillermaterial is conveyed through the filler tube 84F into the interior 28Iof the envelope 16E through a tissue prosthesis component in the form ofa filler valve 106V. The filler valve 106V will be described in greaterdetail below.

As the filler material enters the interior 28I of the envelope 16E, itcauses the envelope 16E to expand to conform to the shape of the cavitywithin the intervertebral disc. It will be appreciated that, due to theresilient flexibility of the envelope 16E, the envelope 16E will readilyconform to the shape of the cavity and the envelope 16E need not be ofany particular pre-configured dimensions.

FIGS. 33-35, illustrate the tissue prosthesis component in the form ofthe filler valve 106V of the envelope 16E that is described in greaterdetail. It is to be noted that the envelope 16E has a bulbous bodyportion 108 (FIG. 32) integrally formed with a neck portion 110N. Theenvelope 16E is attached to the distal end of the carrier tube 14C viathe neck portion 110N. The valve 106V is received within the neckportion 110N of the envelope 16E. The valve 106V is a duck bill valvehaving a pair of opposed operating members or operating flaps 112O. Theoperating flaps 112O, when in their rest condition, as shown in FIGS.33-35 or the drawings, do not close fully and a slit 114S is definedbetween the operating flaps 112O of the valve 106V. This is desirable sothat, prior to filler material being charged into the interior 28I ofthe envelope 16E, air can be withdrawn from the interior 28I of theenvelope 16E via the slit 114S using the syringe 62S.

Once the filler material has filled the interior 28I of the envelope16E, it occludes the slit 114S or, instead, presses down on theoperating flaps 112O to cause them to deform to close the slit 114S.Also, the filler material could have sufficient viscosity to inhibitextrusion of the filler material outwardly through the slit 114S. Itwill be appreciated that, once the filler material has set, it no longermatters whether or not the slit 114S is fully closed.

To inhibit overfilling of the envelope 16E, the envelope 16E is mountedon the carrier tube 14C such that as the envelope 16E fills with tillermaterial, any excess filler material will “extrude” between the neckportion 110N of the envelope 16E and the carrier tube 14C causing theenvelope 16E to be released from the carrier tube 14C.

After the desired quantity of filler material has been charged into theenvelope 16E, the second assembly 82SE is detached from the firstassembly 10FA by breaking the magnetic bond between the magnetic mounts44M and 92M. The filler tube 84F is withdrawn from the interior of thecarrier tube 14C.

The envelope 16E is detached from the carrier tube 14C by relativedisplacement between the carrier tube 14C and the push-off tube 18P.More particularly, the carrier tube 14C is withdrawn from the push-offtube 18P by detaching the collar 40C of the Y-connector 42B from thecollar 36CO of the push-off tube 18P and withdrawing the carrier tube14C. This causes the proximal end of the neck portion 110N of theenvelope 16E to come into abutment with the distal end of the push-offtube 18P causing detachment of the envelope 16E from the carrier tube14C. The push-off tube 18P is then removed. The tissue prosthesis 134P(FIGS. 36 and 37), comprising the envelope 16E filled with the fillermaterial, is retained in position within the intervertebral disc 124D ofthe patient. Additional methods for removing the envelope may include,for example, an external or internal cutting mechanism on the tubeswhich can sever the implant from the delivery apparatus, means oftwisting and crimping the neck of the implant (in certain embodiments,this may both seal and detach the implant, and if the means in which theenvelope is held onto the carrier tube is purely an interference fit orjust tight fit, then pulling on the carrier tube 14C can result indetachment of the envelope (the tube can also be rotated to detach).

As shown in FIGS. 36 and 37, after removal of the carrier tube 14C, atleast a part of the neck portion 110N of the envelope 16E may protrudethrough the annulus 126AN of the intervertebral disc 124D. In addition aresidue of filler material may be present in the distal end of theworking cannula 22C. Therefore, prior to removal of the working cannula22C, an obturator 136O is inserted into a lumen 138L of the cannula 22C.The obturator 136O comprises a blunt-ended rod 140RO which is a tightfit within the lumen 138L of the cannula 22C.

The obturator 136O is used to urge any residue of filler material intothe disc cavity 122D and/or to tamp the part of the neck portion 110N ofthe envelope 16E into the disc cavity 122D, as shown in FIG. 37. Theprosthesis 134P is thus entirely contained within the disc cavity 122Dwith minimal, if any, protrusion into the annulus 126AN of the disc124D.

The obturator 136O can, if desired, be locked to the working cannula 22Cby an attachment collar 142C carried at a proximal end of the obturator136O locking to the collar 32C of the working cannula 22C in a bayonetfitting manner. This allows the obturator 136O to be retained inposition during setting of the filler material and inhibits extrusion offiller material from the envelope 16E and/or from the disc cavity 122D.After completion of the tamping and setting process, the working cannula22C and the obturator 136O are removed.

Tamping the neck portion 110N of the envelope 16E into the disc cavity122D inhibits prosthesis expulsion and excessive loading on the aperture132AN in the annulus 126AN of the disc 124D. In addition, the fact thatthere is no remnant of the envelope 16E in the annulus 126AN enhancesclosure of the aperture 132AN in the annulus 126AN.

It is an advantage of this (and other embodiments) that a tissueprosthesis insertion system is provided which is simple to operate by aclinician. The assemblies are easily connected together using themagnetic connection which improves the stability of the device andobviates the need for relative rotation of the assemblies relative toone another to connect them together. In addition, the use of theprotective sheath protects the envelope against damage while it is beinginserted into and positioned in the patient's body. The sheath isrelatively simple to operate by the clinician thereby improving theperformance of the system as a whole. Further, the use of the syringe asa low pressure generating device simplifies the system and precludes theneed for complicated pumps, etc. Also, due to the fact that the syringeprovides a closed system, it is not necessary to continuously withdrawgas out of the envelope while it is being charged with filler material.This further simplifies operation of the system.

Referring to FIGS. 38A, 38B and 39, reference numeral 10P generallydesignates another exemplary embodiment of a prosthesis delivery system.The prosthesis delivery system 10P includes a plurality of nested tubes12N shown in FIG. 39. In some embodiments, the nested tube will be 3, 4,5, or 6. A cannula or outermost tube 14O of the nested tubes 12N,functions as a cannula in which the remaining tubes are received. Theremaining tubes form part of a prosthesis delivery apparatus 16P. Thetubes of the nested tubes 12N have a flared wall portion 18F. The flaredwall portion 18F of the nested tubes mates 12N with a tapered end 20T ofa static mixer 22S of a dispensing arrangement 24D of the apparatus 16Pof the system 10P

The cannula 14O further includes a manipulating arrangement 26M,arranged at a proximal end of the cannula 14O, for connecting andeffecting manipulation of the nested tubes 12N.

An outermost or first tube 14O of the nested tubes is the cannula whichis used for insertion of the prosthesis delivery apparatus 16Ppercutaneously to a site in which a prosthesis is to be inserted.

The system 10FA is intended for use in the insertion of anintervertebral disc nucleus prosthesis in position in a disc afterperformance of a nucleotomy, if necessary, on a disc to remove thenatural nucleus of the disc. The nucleus may have herniated through anannulus of the disc due to degeneration of the disc. In suchcircumstance, it may not be necessary to perform a nucleotomy on thedisc.

The prosthesis includes an envelope 28E. The envelope 28E is carried onthe end of a carrier tube 30CA. The envelope 28E is an expansibleenvelope of an elastically deformable material which is charged with afiller material to fill a cavity of the disc left by removal of thenatural nucleus. Typically, the envelope is of a silicone material whichis capable of expanding up to 100%, 200%, 300%, 400%, 500%, 6005, 700%,800%, 900%, 1000% its relaxed state without plastically deforming. Thefiller material used with the envelope 28E is also of a siliconematerial and is dispensed from a dispenser 32C of the dispensingarrangement 24D. The filler material is charged into the envelope 28E,in use through a filler tube 34F. The filler tube 34F is nested withinthe carrier tube 30CA.

A further tube 36F is arranged outwardly of the carrier tube 30CA and isused to push off the envelope 28E from the carrier tube 30CA after beingfilled with the filler material and the filler material has at leastpartially set or cured.

It will be noted that, in this embodiment, each of the tubes 14O, 30CA,34F and 36F has the flared portion 18F so that all the tubes mate withthe tapered end 20T of the static mixer 22S of the dispensingarrangement 24D. Further, a proximal portion of the nested tubes 12Nprojects proximally of the tapered end 20T of the static mixer 22S tosurround the static mixer 22S as shown in FIG. 38. The tubes 14O, 30CA,34F and 36F are locked together once nested. Further, the tubes 30CA and34F may seal hermetically once nested and locked together.

The manipulating arrangement 26M of the cannula 14O includes a rupturingmechanism for rupturing the cannula 14O after placement of a distal endof the prosthesis delivery apparatus 16P. The rupturing arrangementcomprises at least a pair of opposed longitudinally extending lines ofweakness, one of which is shown at 38W in FIG. 39. The other line ofweakness is diametrically opposed to the shown line of weakness 38W. Thelines of weakness 38W, divide the cannula into two shells 40S and 42S.The manipulating arrangement 26M comprises a pair of opposed tabs 44T.Each tab 44T is integrally formed with one of the shells 40S, 42S of thecannula 14O. The tabs 44T are used for connecting the nested tubes 12Nto the cannula 14O. Also, by pulling radially on the tabs 44T, thecannula 14O ruptures along the lines of weakness 38W facilitatingwithdrawal of the cannula 14O from the prosthesis delivery apparatus16P.

A gap 46G (FIG. 39) is defined between the carrier tube 30CA and thefiller tube 34F. The gap 46G communicates with a port 48PO (FIG. 38) andwith the interior of the envelope 28E. The port 48PO, in use, forms partof a boss 50BO and a fluid manipulation apparatus (not shown isconnected to the port 48PO to enable the interior of the envelope 28E tobe manipulated either prior to or as the filler material is charged intothe envelope 28E.

The silicone used for expanding the envelope 28E is of the type which,prior to use, is maintained in two separate parts. Thus, the dispenser32C has at least two compartments 52CO, in each of which one part of thesilicone material is stored, prior to being fed through the static mixer22S, where mixing of the parts takes place, and being charged into theenvelope 28E.

In use, an incision is formed in the skin of the patient. The cannula14O, with a trocar (not shown) contained in a lumen of the cannula 14O,is inserted through the incision to the disc on which the operation isto be performed. The trocar is used to perform an annulotorny on anannulus of the disc. Once that operation has been completed, the trocaris withdrawn. A device (not shown) is inserted through the cannula 14Oto perform the nucleotomy, if necessary. The device could, for example,be a mechanical device such as a reamer to ream the degenerative nuclearmaterial from the intervertebral disc.

After completion of the nucleotomy, the device is withdrawn. Theprosthesis delivery apparatus 16P is then inserted into the lumen of thecannula 14O and the envelope 28E is inserted through the annulotomyaperture into the cavity of the disc formed as a result of thenucleotomy. The filler material is dispensed from the dispenser 32C,through the static mixer 22S and the filler tube 34F into the interiorof the envelope 28E while, simultaneously, a lower pressure ismaintained on the port 48PO and the gap 46G.

In an embodiment, the cannula 14O is then removed by rupturing it alongthe lines of weakness 38W by pulling radially outwardly on the tabs 44T.

Once this has occurred, the push off tube 36F is free to be manipulatedrelative to the carrier tube 30CA by being urged in a direction of arrow54AR (FIG. 39) by means of a manipulating ring 56M carried at a proximalend of the push off tube 36F. Pushing off the envelope 28E from thecarrier tube 30CA allows the prosthesis delivery apparatus 16P to bewithdrawn from the patient's body.

In another embodiment, the cannula 14O remains in place. The envelope28E is pushed off from the carrier tube 30CA by withdrawing the carriertube 30CA relative to the push off tube 36F in a direction opposite tothe arrow 54AR. The cannula 14O is the final item to be removed with theremaining nested tubes 12N still contained in and attached to thecannula 14O.

FIGS. 40-42, illustrates certain embodiments of a prosthesis deliverysystem 10P, in this embodiment, the system 10P includes a furthercomponent in the form of a cover tube 60C (FIG. 40). The cover tube 60Cconstitutes a sheath and, at least initially, protects the envelope 28Eof the prosthesis when it is inserted into the cannula 14O.

For this purpose, a distal end of the cover tube 60C is slotted, asshown by slots 62SL. In these embodiments, two slots 62SL are providedto define a pair of opposed resiliently flexible leaves 64LE. The leaves64LE are able to be displaced outwardly in the direction of arrows 66A.Thus, in use, the cover tube 60C, which has substantially the samelength as the cannula 14O, is placed over the prosthesis deliveryapparatus 16P so that the envelope 28E is received between the leaves64LE at the distal end of the cover tube 60C. The entire prosthesisdelivery apparatus 16P including the cover tube 60C, is then insertedinto the cannula 14O and the distal end of the cover tube 60C protectsthe envelope 28E.

The cover tube 60C is arranged between the cannula 14O and the push-offtube 36F. It will, however, be appreciated that, if the cover tube 60Cis appropriately dimensioned, it can, itself, act as the push-off tube,the push-off tube 36F then being omitted.

A proximal end of the cover tube 60C, carries connectors 68C. Theseconnectors 68C engage with the tabs 44T of the cannula 14O so that thecover tube 60C engages with and connects to the cannula 14O to enablethe remaining tubes of the nested tubes 12N to move towards a distal endof the nested tubes 12N so that the envelope 28E can protrude beyond theend of the cover tube 60C and the distal end of the cannula 14O as shownin FIG. 38 of the drawings. The tabs 44, in turn, engage with themanipulating ring 56M to retain the cannula 14O in position relative tothe prosthesis delivery apparatus 16P.

In the embodiment shown in FIG. 41, the cover tube 60C has a flaredportion 18F to nest with the remaining tubes 12N of the prosthesisdelivery system 10P.

In FIG. 42 of the drawings, a set of nested tubes 12N is provided whichdoes not have the flared portion 18F and is mountable to a distal end ofthe static mixer 22S.

It is an advantage of these embodiments that the cover tube 60C obviatesthe need for lubricants to enable the envelope 28E to be inserted into alumen of the cannula 14O. The cover tube 60C serves to protect theenvelope 28E as the prosthesis delivery apparatus 16P is inserted intothe cannula 14O.

It will be appreciated that this embodiment, in use, the incision is ofsuch a size that at least part of the static mixer 22S can be insertedthrough the incision. Due to the flared portion 18F of the nested tubes12N, the overall length of the prosthesis delivery apparatus 16P and thesystem 10P, itself is significantly shorter than would otherwise be thecase. Because of this, the entire system 10P has improved stability andbalance. The stability and balance improves because the lever arm of thesystem (with the pivot point of the system being at the docking point atthe annulus) has now decreased. Since the length of the system hasshortened, the length which the material must travel to the envelopedecreases, therefore the pressure required to deliver the material alsodecreases. Due to the decreased delivery pressure, the surgeon requiresless work (effort) to deliver the material. Less effort means that thesurgeon's movements are more stable and less jerky. This stabilityallows the clinician a higher degree of control in maneuvering thesystem 10P both to the site at which the prosthesis is to be deliveredas well as while forming the prosthesis at the site. This is enhanceddue to the fact that the nesting of the tubes 12N about the static mixer22S also improves the rigidity of the entire system 10P resulting inless free movement of a distal end of the prosthesis delivery apparatus16P of the system 10P. This further enhances the clinician's controlover the system 10P. Since the working cannula is fixed and dockedrelative to the patient, and all the other nested tubes lock to theworking cannula, the positioning and deployment of the envelope withinthe disc space is consistent and repeatable. Also, since all the tubesare fixed relative to each other, during any process of the implantprocedure, the risk of damage to the envelope is minimized becausemovement (laterally and or axially) of the envelope is minimized.Excessive movement of the envelope during any part of the implantprocedure increases its chances of being damaged by either thesurrounding tissue or other tubes (in particular the working cannula).

In certain embodiments, there is provided an intervertebral disc implantwhich includes an envelope constructed of at least one stretchableand/or elastically deformable elastomeric material, the envelopeincluding an attaching formation for attachment to an introducer toenable the envelope, in a collapsed state, to be introduced into avolume of an intervertebral disc that has undergone a nucleotomy; and afiller material receivable in the envelope via the introducer to causethe envelope to expand elastically to conform substantially to thevolume in which the envelope is received, in use.

In certain embodiments, there is provided an intervertebral disc implantwhich includes a first object constructed of at least one stretchableand/or elastically deformable elastomeric material, the first objectbeing in communication with second object for attachment to a thirdobject to enable the first object, in a first state, to be introducedinto a volume of an intervertebral disc that has undergone a nucleotomy;and a material receivable in the first object via the second objectwhich results in expansion, or partial expansion of the first objectsuch that the first object substantially conforms to the volume in whichthe first object is received, in use.

In certain embodiments, there is provided an intervertebral disc implantwhich includes an envelope constructed of at least one stretchableand/or elastically deformable elastomeric material, the envelopeincluding means for attaching an introducer to enable the envelope, in acollapsed state, to be introduced into a volume of an intervertebraldisc that has undergone a nucleotomy; and means for introducing a fillermaterial into the envelope via the introducer to cause the envelope toexpand elastically to conform substantially to the volume in which theenvelope is received, in use.

In some embodiments, the envelope is of a silicone material. In someaspects, the envelope is constructed with at least one siliconematerial.

In some embodiments, the attaching formation may comprise a filler tubemountable to the introducer, the attaching formation may include aclosure device to inhibit back flow of filler material. In someembodiments, the attaching formation may comprise a filler tube incommunication with the introducer, the attaching formation may include aclosure device to inhibit back flow of filler material. In some aspects,the attaching formation may comprise a filler tube in communication withthe introducer, the attaching formation may comprise a closure means forinhibiting back flow of filler material. Any suitable closure device maybe employed such as, for example, but not limited to, a one-way, ornon-return, valve, a filler tube extending outwardly from the remainderof the envelope to be closed off in a suitable manner or a filler tubeextending into the interior of the envelope and which is crimped closedby the surrounding filler material upon withdrawal of the introducer.

In certain embodiments, the filler material may comprise a plurality ofdiscrete, biocompatible, or substantially biocompatible elements. Theelements may include, singly or in combination, beads, pellets, elongateelements, irregular shaped elements, collapsible elements, expansibleelements, preformed elements, shape memory elements, partially curedelements, uncured elements, cured elements. The elements may bebiocompatible elastomers, biocompatible plastics (e.g. silicone),biocompatible metals, biocompatible ceramics, organic or biologicalelements, or a combination of the foregoing. Further, the elements maybe provided in a mixture of sizes.

The elongate elements may be selected from the group consisting offibres, lengths of filamentary elements such as lengths of string,bristle carrying elements such as bottle brush-like elements, andhelical elements such as lengths of coiled wires, or combinationsthereof.

The discrete elements may be arranged in suspension in a filler withinthe volume. In certain aspects, the filler is an elastomeric, curablefiller.

In certain aspects, each expansible element may be configured to changefrom a first configuration for insertion into the envelope to a secondconfiguration which causes the envelope to conform substantially to thevolume. In certain aspects, the at least one expansible element may beconfigured to change from a first configuration for insertion into theenvelope to a second configuration. In certain aspects, at least oneexpansible element may be configured to change from a firstconfiguration into a second configuration wherein the secondconfiguration causes the envelope to partially conform to the volume.Further, each expansible element may be configured to be received, inits first configuration, in the introducer for introduction into theenvelope.

In certain embodiments, each expansible element may, in its restcondition, adopt its second configuration. Further, each expansibleelement may include a biocompatible, shape memory alloy, such as, butnot limited to nitinol, which causes the element to adopt its secondconfiguration in the envelope after ejection from the introducer.

In certain embodiments, the filler material may be a foamed materialwhich is introduced in a compressed state via the introducer into theinterior of the envelope where it expands to its relaxed state to causethe envelope to conform to the volume. In certain embodiments, thefiller material may be contain at least one foamed material which isintroduced in a first state via the introducer into the interior of theenvelope where it expands to a second state to cause the envelope toconform, or substantially conform, to the volume. The foamed materialmay be a polymeric material such as a polyethylene.

In certain embodiments, the filler material may comprise a plurality ofdiscrete bands of a resiliently flexible material. In certainembodiments, the filler material may comprise at least in part aplurality of discrete bands of a resiliently flexible material. Thebands may be configured to be arranged concentrically within theenvelope. The bands may have a height approximating that of the volume.

In certain embodiments, the envelope may carry at least one layer of atissue ingrowth material. In certain embodiments, the envelope may alsoincluding, tissue ingrowth materials. In some aspects, where a layer isused, the layer may be a polyester material such as Dacron (RegisteredTrade Mark).

In certain embodiments, there is provided an intervertebral disc implantwhich includes an envelope, the envelope including an attachingformation for attachment to an introducer to enable the envelope, in acollapsed state, to be introduced into a volume of an intervertebraldisc that has undergone a nucleotomy; and a filler material receivablein the envelope after placement of the envelope in the volume of thedisc, in use, to cause expansion of the envelope to conform to thevolume, the filler material comprising a plurality of discrete, elongateelements introducible, via the introducer, into an interior of theenvelope.

The envelope may be of an expansible material such as an elastomericmaterial having an elongation of at least 100% and, in some aspects, upto about 1000%, for example, silicone. Elastomeric materials such assilicone can have an elongation up to 250%, 500%, 750%.

In certain embodiments, there is provided an intervertebral disc implantwhich includes an envelope, the envelope including means for attachmentto an introducer to enable the envelope, in a collapsed state, to beintroduced into a volume of an intervertebral disc that has undergone anucleotomy; and a filler material receivable in the envelope and meansfor placement of the envelope in the volume of the disc, in use, tocause expansion of the envelope to conform to the volume, the fillermaterial comprising a plurality of discrete, elongate elementsintroducible, the introducer means, into an interior of the envelope.

The envelope may carry at least one layer of a tissue ingrowth material.Further, the envelope, in certain embodiments, may define a filleropening and may include a closure element for closing the opening afterintroduction of the filler material. In certain aspects the envelope mayhave a filler opening means and may include a closure means for closingthe opening after introduction of the filler material.

In certain embodiments the elongate element may be selected from thegroup consisting of fibres, lengths of filamentary elements, bristlecarrying elements and helical elements, or combinations thereof.

The elongate elements may be arranged in suspension in the filler withinthe volume. In some embodiments, the filler may be an elastomeric,curable filler.

In certain embodiments, the elongate elements may comprise a pluralityof discrete bands of a resiliently flexible material. The bands may beconfigured to be arranged concentrically within the envelope.

In certain embodiments, the elongate elements may be expansibleelements. Each expansible element may be configured to change from afirst configuration for insertion into the envelope to a secondconfiguration which causes the envelope to conform substantially to thevolume. Each expansible element may be configured to be received, in itsfirst configuration, in the introducer for introduction into theenvelope. Further, each expansible element may, in its rest condition,adopt its second configuration.

In certain embodiments, there is provided an intervertebral disc implantwhich includes an envelope of a stretchable and elastically deformableelastomeric material the envelope including an attaching formation forattachment to an introducer to enable the envelope, in a collapsedstate, to be introduced into a volume of an intervertebral disc that hasundergone a nucleotomy; and a filler material receivable in the envelopevia the introducer to cause the envelope to expand elastically toconform substantially to the volume in which the envelope is received,in use, the filler material being a foamed material which is introducedin a compressed state via the introducer into the interior of theenvelope where it expands to its relaxed state to cause the envelope toconform to the volume.

The foamed material may be a polymeric material. The envelope may carryat least one layer of a tissue ingrowth material. The envelope maydefine a filler opening and may include a closure element for closingthe opening after introduction of the packing material.

In certain embodiments, there is provided an intervertebral disc implantwhich includes an envelope, the envelope including an attachingformation for attachment to an introducer to enable the envelope, in acollapsed state, to be introduced, in a minimally invasive manner, intoa volume of an intervertebral disc that has undergone a nucleotomy; anda filler material receivable in the envelope after placement of theenvelope in the volume of the disc, in use, to cause expansion of theenvelope to conform to the volume, the filler material comprising, incombination, a curable filler material and a plurality of discrete,biocompatible elements contained, in use, in the filler material withinthe envelope.

The elements may include, singly or in combination, beads, elongateelements and expansible elements. The elongate elements may be selectedfrom the group consisting of fibres, lengths of filamentary elements,bristle carrying elements and helical elements.

Each expansible element may be configured to change from a firstconfiguration for insertion into the envelope to a second configurationwhich causes the envelope to conform substantially to the volume.Further, each expansible element may be configured to be received, inits first configuration, in the introducer for introduction into theenvelope. Each expansible element may, in its rest condition, adopt itssecond configuration.

The filler may be an elastomeric, curable filler.

In certain embodiments, there is provided an intervertebral disc implantwhich includes an envelope of a stretchable and elastically deformableelastomeric material, the envelope including an attaching formation forattachment to an introducer to enable the envelope, in a collapsedstate, to be introduced into a volume of an intervertebral disc that hasundergone a nucleotomy; and a filler material receivable in the envelopevia the introducer to cause the envelope to expand elastically toconform substantially to the volume in which the envelope is received,in use, the filler material being an elastomeric material having aviscosity of at least 500 cP. In certain aspects, the filler materialmay have a viscosity of at least 1000 cP, of at least 5000 cP, of atleast 10000 cP, of at least 50000 cP, of at least 100000 cP, of at least500000 cP.

In certain embodiments, there is provided an intervertebral disc implantwhich includes an envelope receivable in a volume of an intervertebraldisc that has undergone a nucleotomy, the envelope defining a pluralityof chambers, the chambers being configured so that, when at leastcertain of the chambers contain a filler material, the envelope conformssubstantially to the volume of the disc; a filler material receivable inthe at least certain of the chambers; and at least one of the chambershaving a filler mechanism associated with it.

The chambers may be defined by wall portions of the envelope, wallportions of some of the chambers being of a different wall thicknessthan wall portions of other chambers. In addition, wall portions of someof the chambers may be of a different material than wall portions ofother chambers. Still further, the filler material receivable in atleast one of the chambers may differ from the filler material that isreceivable in at least one other of the chambers.

The envelope may include an attaching formation for attachment to atubular introducer to enable the envelope, in a collapsed state, to beintroduced, in a minimally invasive manner, into the volume of the disc.

Each chamber in which filler material is receivable may have a fillermechanism associated with it. The filler mechanism may be a one-waydevice that, upon closure, inhibits back flow of filler material.Preferably, the filler mechanism of an outer chamber of the envelope maybe implemented as the attaching formation.

In certain embodiments, the system for implanting an intervertebral discimplant, comprises:

an implant as disclosed herein; and an introducer, the introducercomprising a plurality of filler tubes, each tube communicatingindependently of any other tube with its associated chamber of theenvelope for charging filler material into the associated chamber.

In certain embodiments, there is provided an intervertebral disc implantwhich includes at least one element which changes from a firstconfiguration for insertion into a volume of an intervertebral disc thathas undergone a micleotomy to a second configuration in which the atleast one element conforms substantially to the volume, the at least oneelement being configured to be received, in its first configuration, inan introducer to be inserted into the volume of the disc.

The at least one element, in its first configuration, may be elongateand, in its second configuration, may adopt a shape conformingsubstantially to the volume. The at least one element may include abiocompatible, shape memory alloy which causes the element to adopt itssecond configuration in the volume after ejection from the introducer.

Further, in certain embodiments, the at least one element, in itsrelaxed state, may be in the first configuration, the at least oneelement including a retention device for retaining the at least oneelement in the second configuration after ejection from the introducer.

In certain embodiments, the implant may include an envelope receivablein a collapsed state in the volume; and a plurality of the elementsreceivable in the envelope, the plurality of elements causing theenvelope to expand substantially to conform to the volume.

In certain embodiments, there is provided a system for implanting anintervertebral disc implant as disclosed herein the systems including anintroducer having a proximal and a distal end, a mount for the envelopeof the implant being arranged at or adjacent the distal end of theintroducer; a source of filler material connectable to the proximal endof the introducer, and a displacement mechanism for displacing thefiller material along the introducer to be ejected from the introducerinto the envelope, in use.

The introducer may comprise at least one tubular member. Instead, theintroducer may comprise at least two tubular members arranged in atelescopic fashion, the tubular members being reciprocally displaceablerelative to one another.

An innermost one of the tubular members may carry the displacementmechanism. The displacement mechanism may comprise a ratchet arrangementfor urging the filler material along the introducer into the envelope.

Further, the envelope may include a flow control device arranged at aninlet opening to the envelope for inhibiting back flow of the fillermaterial from the envelope. The equipment may include a flow controldefining member, the flow control defining member being separate fromthe envelope and being arranged at the inlet opening to the envelope.

A distal end of the filler member may carry an engaging member whichengages the flow control device to at least partially open the flowcontrol device and to allow the interior of the envelope to bemanipulated prior to being charged with the filler material. Theenvelope may carry a marker arrangement on an exterior surface forenabling the envelope to be used to assess dimensions and a shape of thecavity and positioning of the envelope in the cavity.

The filler material may be of an elastomeric material capable ofabsorbing shock and withstanding compressive, tensile, bending andtorsional forces. The envelope and the filler material may be of anelastomeric material having a Shore Hardness in the range of about 5 to90 A. The shore hardness may be between 5 and 15 A, 15 and 25 A, 25 and35 A, 35 and 45 A, 45 and 55 A, 55 and 65 A, 65 and 90 A. Preferably,the envelope and the filler material are of a silicone rubber material.

The envelope may be of an elastomeric material capable of expanding toup to 3, 4, 5, 10, 25, 50, 75 or 100 times its relaxed state. Theenvelope is preferably expanded to be stretched and retained undertension after being charged with the filler material.

The envelope may include a neck portion, the neck portion defining azone of weakness for facilitating separation of the envelope from thedelivery device. Further, the envelope may include a flow control devicearranged at an inlet opening to the envelope for inhibiting back flow ofthe filler material from the envelope. The equipment may include a flowcontrol defining member, the flow control defining member being separatefrom the envelope and being arranged at the inlet opening to theenvelope.

The envelope may carry a marker arrangement on an exterior surface forenabling the envelope to be used to assess dimensions and a shape of thecavity and positioning of the envelope in the cavity.

The filler material may be of an elastomeric material capable ofabsorbing shock and withstanding compressive, tensile, bending andtorsional forces. More particularly, the envelope and the fillermaterial may be of an elastomeric material having a Shore Hardness inthe range of about 5 to 90 A. The shore hardness may be between 5 and 15A, 15 and 25 A, 25 and 35 A, 35 and 45 A, 45 and 55 A, 55 and 65 A, 65and 90 A. The envelope and the filler material may be of a siliconerubber material.

In certain embodiments, there is provided a tissue prosthesis whichcomprises an envelope of a biologically inert, elastically deformablematerial capable of being expanded to conform to an interior surface ofa cavity formed at a site in a patient's body; and a filler materialreceived in a fluent state in the envelope, the filler material being ofthe same class of material as the envelope to form, when cured, togetherwith the envelope, a unified structure.

The envelope may be of an elastomeric material capable of expanding toup to 3, 4, 5, 10, 25, 50, 75 or 100 times its relaxed state. Further,the filler material may be of an elastomeric material capable ofabsorbing shock and withstanding compressive, tensile, bending andtorsional forces. The envelope may be expanded to be stretched andretained under tension after being charged with the filler material.

Both the envelope and the filler material may be of an elastomericmaterial having a Shore Hardness in the range of between about 5 to 90A. The shore hardness may be between 5 and 15 A, 15 and 25 A, 25 and 35A, 35 and 45 A, 45 and 55 A, 55 and 65 A, 65 and 90 A The envelope andthe filler material may be of a silicone rubber material. Preferably,the envelope and the filler material are of a silicone rubber material.However, to promote bonding between the envelope and the fillermaterial, the envelope and the filler material may be of differentgrades of silicone rubber material and may be pre-treated in differentways prior to use.

The envelope may include a neck portion, the neck portion defining azone of weakness for facilitating separation of the envelope from adelivery device. Further, the envelope may include a flow control devicearranged at an inlet opening to the envelope for inhibiting back flow ofthe filler material from the envelope. In an embodiment, the prosthesismay include a flow control defining member, the flow control definingmember being separate from the envelope and being arranged at the inletopening to the envelope.

The envelope may carry a marker arrangement on an exterior surface forenabling the envelope to be used to assess dimensions and a shape of thecavity and positioning of the envelope in the cavity.

In certain embodiments, there may be provided a tissue prosthesis whichcomprises an envelope of a foraminous, chemically inert material shapedto conform, or substantially conform, to an interior surface of a cavityformed at a site in a patient's body in which the envelope is to beplaced; and a filler material received in a fluent state in theenvelope, the filler material being of an elastomeric material which,prior to being cured, is urged into foramens of the envelope to form anintegrated structure which inhibits relative movement between theenvelope and the filler material, in use, and once the filler materialhas cured.

The envelope may be of a knitted biological or synthetic polymericmaterial. More particularly, the envelope may be of a knitted polyestermaterial, such as polyethylene terephthalate (PET). Further, theenvelope may be coated with a material of the same class as the fillermaterial.

The filler material 60F (see, e.g., FIG. 7) may also be constructed of asilicone rubber material which is able to absorb shocks and withstandcompressive, tensile, bending and torsional forces imparted to it bymovement of the vertebrae 12V and 14V. In addition, due to the fact thatthe filler material 60F is the same class or type as the material of theenvelope 38E, once the filler material has cured in the envelope 38E, aunified or single, integrated structure is formed which is resistant todelamination and relative movement between the envelope 38E and thefiller material 60F.

One component of certain embodiments is the use of at least one envelopeto confine the filler material. Depending on the particular embodiment,the envelope may function to partially contain, substantially contain,or contain the at least one tiller material. The function of theenvelope to contain the filler material may vary from fully containingthe filler material to something less than fully containing the fillermaterial. In certain embodiments, the envelope may be a balloon typestructure, mesh-like structure, a band-like structure, may be comprisedof a multi cavity like structure, may be a foldable structure and/or afoldable structure that has a shape memory or combinations thereof. Insome aspects, the envelope may be expandable and/or stretchable up to50%, 100%, 200%, 300%, 400%, 500%, 600%, 700% or up to 1000%, or greaterthan 1000% of its relaxed volume. In other embodiments, the envelope maybe inelastic, or substantially inelastic. In some aspects of thedisclosed embodiments, means for confining the filler material areprovided. For example, but not limited to, the structures disclosed inthis application. In some embodiments, the envelope may be configured tosufficiently contain the filler material at the desired location beforethe implant, during the method of implant and/or after the implant.

In certain embodiments, the biomaterial may be in the form of abiocompatible or substantially biocompatible polymer compositioncomprising a plurality of parts capable of being aseptically processedor sterilized, stably stored, and mixed at the time of use in order toprovide a flowable composition. In some embodiments, the polymercomposition may contain optionally, other ingredients such asantioxidants, and dyes. In some aspects, upon mixing, the composition issufficiently flowable to permit it to be delivered to the desired siteand there fully cured under physiologically conditions. In some aspects,the component parts are themselves flowable, or can be renderedsufficiently flowable, in order to facilitate their mixing and use.

Additionally, the devices disclosed herein are considered novel in theirown right, and can be used with any suitable biomaterial. In certainembodiments, the devices may be used in combination with a curablesilicone based polymer composition comprising a plurality of partscapable of being aseptically processed or sterilized, stably stored, andmixed at the time of use in order to provide a flowable composition andinitiate cure. Those skilled in the art will, in turn, appreciate themanner in which such polymer compositions can be manipulated to producecured and curing polymers with desired combination of properties withinthe scope of certain embodiments. The silicone can be chemicallycrosslinked, e.g., by the addition of multifunctional or branchedOH-terminated crosslinking agents or chain extenders. The optimal levelof chemical cross-linking improves the compression set of the material,reduces the amount of the extractable components, and improves thebiodurability of the silicone polymer. This can be particularly usefulin relatively soft silicone polymers, such as those suitable for therepair of damaged cartilage. Additional fillers may be added to thepolymer composition such as silica, to alter the hardness, compressionset, tensile strength, tear strength, viscosity, other physical orchemical properties, or combinations thereof. In this manner a balancingof the physical and/or chemical properties with respect to the overallcharacteristics of the polymer, can be achieved.

Additionally, certain polymer systems may contain at least one or more,biocompatible or non biocompatible catalysts that can assist incontrolling the curing process, including the following periods: (1) thescorch time (2) the setting period, and finally, (3) the final cure ofthe biomaterial. Together these three periods, including their absoluteand relative lengths, and the rate of acceleration or cure within eachperiod, determines the cure kinetics or profile for the composition.Suitable examples of the catalyst for the formed polymer will dependupon the polymer material selected. In certain aspects where the polymeris a silicone based polymer the catalyst may be selected from, but notlimited to the following: tin, platinum, peroxide.

As applied to intervertebral disc repair, the inclusion of an “additive”in the prepolymer, previously described and presently preferred byapplicants in formulations for joints other than the disc, is notpresently preferred (though remains optional) for use in the disc. Whenpresent, such an additive can provide several desirable features, bothin the formulation and use of the prepolymer itself, as well as in themixed composition. These features include an improved combination ofsuch properties as moisture cure characteristics, cross-linking,viscosity, compression fatigue, and stability.

Certain preferred compositions provide certain desirable properties,including, but not limited to, compression set, hardness, strength, curecharacteristics and combinations thereof.

When cured, suitable materials can be homogeneous, providing the samephysico-chemical properties throughout, or they can be heterogeneous andexhibit varying features or properties. An example of a heterogeneouscomposition, e.g., for use as an intervertebral disc replacement, is acomposition that mimics the natural disc by providing a more rigid outerenvelope (akin to the annulus) and a more liquid interior core (akin tothe nucleus). Such heterogeneous compositions can be prepared by the useof a single composition. e.g., by employing varying states of cureand/or by the use of a plurality of compositions, including varyingcompositions and/or ratios of the same ingredients used to form thecomposition.

Suitable compositions for use certain embodiments are those polymericmaterials that provide an optimal combination of properties relating totheir manufacture, application, and in situ use. In the uncured state,such properties include component miscibility or compatibility, processability, and the ability to be adequately sterilized or asepticallyprocessed and stored. In the course of applying such compositions,suitable materials exhibit an optimal combination of such properties asflow ability, mold ability, and in situ curability. In the cured state,suitable compositions exhibit a desired combination of such propertiesas strength (e.g., tensile and compressive), hardness, modulus,biocompatibility and biostability.

When cured, certain of the disclosed compositions demonstrate adesirable combination of properties, in terms of their conformationalstability and retention of physical shape, resilience during load andunload conditions in situ, dissolution stability, biocompatibility, andphysical performance, as well as physical properties such as density andsurface roughness, and mechanical properties such as load-bearingstrength, tensile strength, shear strength, shear fatigue resistance,impact absorption, wear resistance, and surface abrasion resistance.Such performance can be evaluated using procedures commonly accepted forthe evaluation of natural tissue and joints, as well as the evaluationof materials and polymers in general. In particular, a preferredcomposition, in its cured form, exhibits mechanical properties thatapproximate or exceed those of the natural tissue it is intended toprovide or replace. In some aspects, certain compositions may be capableof deforming and recovering resiliently in situ without plasticdeformation, or substantial plastic deformation. In some aspects,certain compositions may be capable of deforming and recoveringresiliently in situ with an acceptable level of plastic deformation. Insome aspects, certain compositions may be capable of deforming andrecovering resiliently in situ without compression set, or substantialcompression set.

It should be appreciated that certain compositions may be produced thathave a desired combination of the physical and chemical propertiesdiscussed in this application.

With respect to those polymer compositions that are uncured, componentsof such compositions, and the compositions themselves, should bemiscible, compatible and stable under conditions used for sterilizationand during storage and in the course of delivery. They are also capableof flowing to an in situ location, and being cured in situ, using asuitable catalyst, thereafter the cured composition is suitably amenableto conforming, shaping and/or contouring, by the use of the deviceembodiments disclosed herein. Over the course of its use in the body thecured, contoured composition exhibits physiological, physical-chemicaland mechanical properties suitable for use in extended in situapplications.

To achieve these desirable uncured and delivery properties, a “polymersystem”, as used herein refers to the component or components used toprepare a polymeric composition. In an embodiment, a polymer systemcomprises the components necessary to form two parts (as discussedelsewhere herein, together with other ingredients (e.g., catalysts,stabilizers, plasticizers, antioxidants, dyes and the like). Suchadjuvants or ingredients can be added to or combined with any othercomponent thereof either prior to or at the time of or after mixing,delivery, and/or curing.

In choosing an optimal volume ratio for a given formulation, thefollowing may be taken into consideration. The viscosity of the reactiveparts in this temperature range of less than about 10° C., less thanabout 20° C., less than about 30° C., less than about 40° C., less thanabout 50° C., less than about 70° C., must be such to provide anacceptable degree of mixing and injection flow rate without mechanicalfailure of any component of the delivery system including cartridge,static mixer, gun and other components. Preferably, the biomaterial issufficiently flowable to permit it to be delivered (e.g., injected) intothe balloon). While such a material can be as thick as the bone cementpaste, the preferred viscosity is less than 1000 Pa·s, 100 Pa·s, 80Pa·s, 60 Pa·s, 40 Pa·s, 20 Pa·s, 15 Pa·s, 10 Pa·s, 8 Pa·s, or 6 Pa·s. Insome aspects, one preferred viscosity is less than 100 Pa·s. Thecomposition of both reactive parts must be such that these parts arehomogeneous and phase stable in the temperature range of theapplication. The max temperature of the reaction exotherm isproportional to the concentration of the reactive groups in the mixedpolymer. A high concentration of the reactive groups might evolve toohigh reaction exothermal energy and therefore may cause thermal damageto the surrounding tissues. The preferable implant-tissue interfacetemperature is below 70° C., 50° C., or more preferable below 40° C. Itis desirable in some embodiments that the reactive parts stay liquid, orsubstantially liquid, during mixing. The complete or partialsolidification of the reactive part when it comes into contact withanother reactive part or any component of the delivery system or duringmixing may be unacceptable. The certain volume ratio of the componentscan be achieved by different ways such as use of the dual-compartmentcartridges with constant volume ratio or by using the injectors withdelivery rates independently variable for each component.

Many mixing devices and methods have been used for multiple partbiomaterials, such as bone cement and tissue sealant, used in operatingrooms. Static mixers and manual dispenser guns are commonly used fortissue sealant and other multi-component biomaterial mixing anddelivery.

It is important that the two parts of polyurethane pre-polymer are mixedquickly and completely in the operating room in a sterile fashion. Thenumber of mixing elements may vary and depends on the composition of theselected polymer. For example, with certain silicone based polymers, itis possible to use between 6 and 20 mixing elements, between 8 and 15mixing elements, or between 10 and 12 mixing elements.

In certain embodiments, in situ curability may be dependent on thereaction rate, which can be measured by induction time and cure time. Ingeneral, fast cure (short induction time) will improve in situcurability and result in less leachable components. However, inductiontime should also be balanced with adequate working time needed forpolymer injection.

A cured biomaterial of that may be used with certain embodimentspreferably exhibits a compression modulus of between about 0.1 MPa andabout 50 MPa, and more preferably between about 1 MPa and about 25 MPa,when measured using ASTM method D575 A at a physiological strain rangebetween 3 and 20%. In certain embodiments, compositions having acompression modulus considerably below these levels will tend to eitherbulge or extrude from annular defects that may exist or appear, whilethose having a modulus considerably above these levels will tend to betoo hard and cause stress shielding and abnormal high contact stress onthe endplate.

In certain embodiments, the envelope 38E is made from a silicone rubbermaterial having the following characteristics:

a Shore hardness (A scale) in the range from about 20-50;

a tensile strength in the range from about 2700 kPa to 11000 kPa;

an elongation of between about 400% and 800%; and

a tear strength of between about 1700 kg/m and 4500 kg/m.

The filler material 60F is also of a silicone rubber material which,prior to use, is stored in two separate parts. The filler material 60F,comprising the combined parts, when mixed in a ratio of 1:1 and cured,has the following characteristics:

a Shore hardness (A scale) in the range from about 20 to 40, moreparticularly, about 25 to 30 and, optimally, about 28;

a tensile strength in the range form about 7000 kPa to about 9500 kPa,more particularly, about 8000 kPa to about 9000 kPa and, optimally,about 8500 kPa;

an elongation in the range from about 550% to 700%, more particularly,about 600% to 650% and optimally, about 640%; and

a tear strength in the range from about 1000 to 2000 kg/m, moreparticularly, about 1250 kg/m to 1750 kg/m and, optimally, about 1500kg/m.

One example of a suitable material for the filler material has thefollowing characteristics after mixing the parts in a 1:1 ratio andafter curing:

a Shore hardness (A scale) of 28;

a tensile strength of 8439 kPa;

an elongation of 639%; and

a tear strength of 1500 kg/m.

The filler material 60F may be treated to contain 5%, by volume, bariumsulphate to appear radio-opaque under X-ray, CT, fluoroscopy and MRI. Inaddition, the filler material 60F contains a catalyst and has a scorchtime of between about 1.5 to 2.5 minutes with a curing time of about 5minutes. When the filler material 60F is charged into the envelope 38Eit causes inflation or expansion of the envelope 38E in an elasticallydeformable manner. Expansion of the envelope 38E can occur to such anextent that, where necessary, the expanded envelope 38E distracts thevertebrae 12V and 14V to restore the original spacing between thevertebrae 12V and 14V. By using radio-opacity in the filler material60F, distraction of the vertebrae 12V and 14V can be monitored in realtime using a fluoroscope or similar equipment.

Further, the envelope 38E conforms to the shape of the cavity 36C.Because the envelope 38E expands within the cavity 36C and conformsclosely to the shape of the cavity 36C, the envelope 38E self anchorswithin the cavity 36C and “extrusion” of a unified prosthesis 100P,comprising the envelope 38E and the filler material 60F, formed throughthe aperture 30A previously formed in the annulus 16A of the disc isinhibited.

The material for the envelope may, depending on the grade or class ofmaterial used, be post cured for a period of time. This is effected byplacing the moulded envelope 38E into an oven, for example, for a periodof about 1 to 4 hours at a temperature of about 150° C. to 180° C.

By having the material of the envelope 38E and the filler material 60Fof the same type, but different grades or classes, chemical bondingbetween the materials is enhanced which encourages the formation of theprosthesis 100P.

An embodiment of the biomaterial was studied to characterize themechanical and wear behavior of the implant.

Fatigue testing was performed to evaluate the mechanical and wearperformance of the implant over its intended life. Fatigue testing incompression, flexion/extension, lateral bending and axial rotation wereconducted to mimic in vivo physiological ranges. Specimens were loadedto 10 million cycles in compression as suggested by ASTM 2346-05 and 5million cycles in flexion/extension, lateral bending and axial rotation.

The test implant was an annulus model (Silicone Shore Hardness 60 A)with a complete implant (filler material—CSM-2186-14 (NusilTechnologies) and jacket material—MED-4830 (Nusil Technologies) and CalfSerum 30 g/L solution (as per ISO/DIS 18192-1)) injected according toexpected surgical procedure. Six implants were created.

The annulus model was placed between two Perspex constraining plateswhich prevent the model from bulging superiorly and inferiorly. Throughthe annulotomy, the implant was delivered using the equipment describedherein until the implant had completely filled the cavity of the annulusmodel. The annulus model and the implant was placed inside a water bathset to 37° C. and let to cure for at least 1 hour.

6 specimens were glued to the test platens and left to dry for 24 hours.The specimens and test platens were then connected to thespinesimulator. The test stain was filled with calf senrum andmaintained at 37±3° C.

The test execution was as follows:

1) A compression load of 100N and 600N was applied and the heights ofthe specimens at these loads were measured. This height was taken as thereference heights

2) Specimens were cyclically loaded under the following conditions:

-   -   Compression    -   Load range:    -   100N to 2000N for 10 000 cycles    -   600N to 1500N for 990 000 cycles    -   Load frequency: 2 Hz    -   Flexion/Extension    -   Bending range: +6/−3.degree.    -   Range frequency: 1 Hz    -   Lateral Bending    -   Bending Range: .+−0.2.degree.    -   Range frequency: 1 Hz    -   Axial Rotation    -   Bending Range: .+−0.2.degree.    -   Range frequency: 1 Hz

3) After the completion of the 1 million compression cycles a 100N and600N load was reapplied to measure the height change.

4) This process was repeated another 9 times such that the specimensunderwent 10 million compression cycles.

5) At the completion of the cycling loading the specimens were left torecover for 24 hours a then 100N and 600N load was reapplied to measurethe height change.

After each million compression cycles the calf serum test medium wascollected and analyzed.

Since literature publications have suggested the standing load resultsin approximately 0.5 MPa of pressure in the lumbar discs while discpressures whilst lifting is suggested to be between 1.0 to 2.3 MPa, itwas believed that choosing a loading regime between 600N to 1500N and600N to 2000N would represent a worse case scenario. Theflexion/extension, lateral bending and axial rotations ranges arecomparable to human in vivo conditions as suggested ISO/DIS18192-1. Thefrequency of 2 Hz was chosen so as to not overheat the samples.

In the fatigue test, one of the six specimens was destroyed due to itslipping from the stainless steel platen at about the 5.8 million cyclemark. Tears in the annulus were noticed in all test stations at the 3million cycle mark.

Observations of a nucleus replacement device or CDD implant graded tothe scale below.

Grade 1=Jacket peeling observed

Grade 2=Minor cracks observed

Grade 3=Progression of minor cracks observed

Grade 4=Major crack

Wear particles collected in the test medium were subjected to SEM(Scanning Electron Microscope). The results characterized the size withrespect to shape factor, roundness and equivalent circle diameter. Thetest medium was collected every million cycles and wear particlesextracted. The number of particles found per million cycles wascollated. The number of particles found per sample per million cyclesranged from 137 to 797 particles. The average number of particles permillion cycles was approximately 500 particles. Most particles had ashape factor of between 0.9 and 1 indicating that most of the particlescollated were round. The equivalent circle diameter for most particleswas between 0.1 and 0.3 μm.

EDX (Energy dispersive X-ray spectroscopy) analysis of the wearparticles showed no trace of barium, while silicon, gold and palladiumwere detected. The detection of gold and palladium was due tocontamination via the SEM analysis. A sample of an untested nucleusspecimen was also analyzed under EDX to determine the detectability ofbarium. The analysis showed barium was detected but the wear particlescollected from the fatigue testing did not show any signs of barium.According to supplier of the composition, the barium sulfate particlescontained within the filler material is approximately 1 μm. Hence theEDX analysis is sensitive enough to detect the presence of bariumsulfate particles, but the lack of traces detected by the EDX for theimplant indicated that the implant had not worn, or the wear had notbeen significant enough.

All 5 specimens passed the acceptance criteria which required thespecimens to not split up into more than 3 distinct pieces which aresmaller than the size of the annulotomy. This criterion was chosen asthe mechanical function of the implant will remain even if it has brokenup so long as the implant is adequately constrained within the annulus.So long as the implant is able to maintain its total volume it willstill function as required. The 5 specimens all remained intact in onepiece when the annulus remains essentially intact. In the testsinvolving Specimens 2 and 4 it was noted that the simulated annulusfailed leading to a grading of higher than 1 for these tests at somepoint beyond 5 million cycles. It is noted that a protocol involving thereplacement of the annulus after a set number of cycles, e.g., 2million, may more closely represent the natural regeneration of theannulus that occurs in the body and provide a better measure of theperformance of the implant. In spite of these shortcomings in thesimulated annulus, the structural integrity of the 5 specimens remainedintact after the fatigue testing and hence the acceptance criteria weremet. The EDX analysis on the wear particles generated from the testingprocedure showed no signs of barium or platinum and hence not from thenucleus filler material. The acceptance criteria also required no morethan 10% of the volume lost. From visual observation of the 5 specimens,there were no sites where significant parts of the implants were wornaway. Specimens tested where the annulus model did not fail remainedfully intact with no cracks. The remaining two specimens where theannulus failed had cracks present in them but nonetheless remainedintact as one functional body. Accordingly, the implant is capable ofwithstanding in vivo conditions for 10 years equivalent withsupra-physiological loading.

Supra physiological loads in the lumbar spine may be encountered duringaccidents, thus evaluation of the impact performance of the implant isrequired.

The test set up for shock testing was as follows:

1) Specimens were loaded in compression to 100N to measure the referenceheight.

2) A shock load of 3000N at a rate of 200 kN/min was then applied.

3) Specimens were then unloaded to 100N at a rate of 200 kN/min and holdfor 20 seconds to measure the reference height.

This particular test was performed because a shock load rate of 250mm/min or greater has been suggested by ASTM draft standard WK4863.

Specimen Permanent deformation (mm) 2.1 0.5 2.2 0.5 2.3 0.4 2.4 0.3 2.50.3 2.6 0.4 Mean 0.45 Std. dev. 0.09

The mean permanent height loss for the specimens was 0.45 mm or 3.2%.The permanent deformation of the implant constrained within an annulusmodel is less than 4%.

In vivo, the lumbar discs encounter both static and dynamic loading.Conducting static testing is essential in understanding the creep andrecovery behavior of the implant under a constant load.

1) Specimens were loaded compression to 100N to measure the referenceheight and then unload.

2) Specimens were loaded in compression to 600N and held continuouslyfor 16 hours.

3) A load of 100N was applied to measure the height following staticcreep

4) Specimen was unloaded for 8 hours for recovery.

5) 100N load was reapplied to measure the recovery and permanentdeformation from that measured in step 1.

6) Steps 1 to 5 was repeated.

This test was performed because a 600N load over 16 hours isapproximately equivalent to a person standing continuously for 16 hours.

The loading regime of the specimens aimed to simulate a person standingcontinuously for two 16 hour periods followed by 8 hours of rest over 48hour period. At the first 600N compression load all specimens crept lessthan 0.2 mm over the 16 hour period which is equivalent to less than1.5% height loss. At the second 600N load all test specimens crept lessthat 0.2 mm, again equivalent to less than 1.5% height loss.

The specimens were also subjected to a 100N reference height before thecommencement of testing. The 100N load was also applied before and afterthe 8 hour no load (rest periods). In average height loss at 100N loadat the end of testing was 0.2 mm when compared to the reference height.The maximum height loss at 100N load occurred after the second 600Nloading period and it showed the height loss at this load wasapproximately 0.3 mm when comparing to the reference height.

This indicates the implant looses minimal height after constant staticloading. The static creep of the implant constrained within anartificial annulus model creeps less than 2% over a 16 hour period.

Other nucleus replacement prostheses, mainly hydrogels require fluidabsorption to form the required dimensional characteristics and thusswelling tests are essential in the mechanical characterization process.The implant is not made from a hydro-expanding material. It allows watermolecules to pass through, therefore this test was not considerednecessary. It was included in this protocol for completeness and toverify the above claim.

Specimens were dried in an oven at temperatures above 100 degrees for aminimum of 4 hours.

1) Specimens were placed within a swell test jig with a plastic plateplaced on top.

2) The jig was then filled with Ringer's solution.

3) A LVDT transducer was used to measure the height change over a 48hour period.

Max. sensor Min. sensor Height Change deflection deflection Fluctuationafter 48 hours Specimen (mm) (mm) Range (mm) (mm) 1 0.02 −0.02 0.04−0.01 2 0.01 −0.01 0.02 0.01 3 0.01 0.00 0.01 0.01 4 0.00 −0.02 0.02−0.01 5 0.00 −0.03 0.03 −0.02 6 0.00 −0.02 0.02 −0.01 Mean 0.01 −0.020.02 −0.01 Std. dev. 0.01 0.01 0.01 0.01

The results the mean height change after 48 hours soaking in Ringer'sSolution was 0 mm. The maximum change in height occurred on specimen 5with a 0.03 mm. The results indicate that the implant is not affected byswelling through fluid absorption as opposed to hydrogels.

Previous clinical studies of other prostheses have raised concern withextrusion of the device. Therefore, it is important to evaluate the riskof extrusion with the implant. The proposed surgical procedure used toimplant the implant is through the creation of an annulotomy. Thereforethis extrusion test will be done on a similar sized annulotomy in anartificial annulus model (this being the worst case opening in theannulus). Because of the characteristics of the implant, it is doesn'treally lend itself to extrusion. This test was performed forcompleteness and no extrusion of any kind or severity was expected.

The implant was partially filled to a volume between 1.5 to 2 ml insidethe annulus cavity to represent a worse case scenario since it wasbelieved that partially filled implant specimens have a greater chanceof extrusion due to their relative size to the annulotomy opening.

1) Specimens were fatigue loaded for 200,000 compression cycles underthe following conditions:

-   -   Compression        -   Load range: 600N to 2000N        -   Frequency: 2 Hz    -   Flexion/Extension        -   +6/−3.degree. Frequency: 1 Hz        -   Frequency: 1 Hz

Partially filled implants (30 to 50% fill) were subjected to fatiguetesting in compression and flexion/extension. The position of theannulotomy was positioned such that the annulotomy underwent tensionduring the flexion cycle. During this cycle the implant and theencompassing annulus model are flexed to 6 degrees. This accompaniedwith the compression cycles subjected the implant to conditions thatwould induce expulsion. After 200,000 cycles no expulsions orprotrusions were observed in any of the test specimens. Detachmentbetween the superior section of the annulus and the stainless steel testplaten occurred in specimens 3 and 4 after the 200,000 cycles.

A partially filled implant (30 to 50% fill) was chosen as a smallersample would more likely extrude than a fully filled implant as the sizeof the annulotomy remained the same. Also the implant was inflatedthrough the annulotomy and hence the proximal end of the implant sits atthe inner edge of the annulotomy. In addition to this test, noexpulsions were observed during the fatigue test in which the implantwas subjected to multi directional testing to 10 years equivalent withan annulotomy present. From the literature expulsion studies have beenconducted using cadaveric models. This test was performed in anartificial annulus model as it would allow testing to be conducted to200,000 cycles which would otherwise not be possible in a cadaveric testmodel due to tissue degeneration.

No expulsions or protrusions were observed for all 6 test articles after200,000 cycles hence the acceptance criteria were met. In addition noexpulsions were observed during any point of the fatigue test.

Due to the viscoelastic nature of the implant, it is expected to creepunder an applied load. This test aims to evaluate this. An implantspecimen was filled into a 25.4 mm diameter cylindrical mould toapproximately 10.5 mm in height.

1) The specimen was placed between test platens.

2) The specimen was then subjected to a 253N (0.5 MPa) compression loadfor 16 hours.

3) Specimen was then unloaded (no load applied) for 8 hours to recovery.

4) Steps 2 and 3 were repeated a further three times such that thespecimen was subjected to four 16 hour loading regimes over a four dayper period.

Time Point Height Loss (%) End of first session −3.47 Start of 2^(nd)session −0.71 End of 2^(nd) session −4.18 Start of 3^(rd) session −1.10End of 3^(rd) session −4.44 Start of 4^(th) session −1.69 End of 4^(th)session −4.53

The results show a gradual decrease in height during the loading periods(approximately 3.5% per 16 hour period). During the 8 hour rest periodsthe specimen recovered approximately 80% of the height loss. Duringloading on the fourth day aspects of recovery was observed. The implantshowed signs of permanent deformation and recovery after loading due toits viscoelastic properties.

Conducting mechanical tests on aged samples is critical in ensuring themechanical performance of the implant is not compromised over time.Samples were aged using heat as proposed by the literature. The implantswere aged using a 10 degree temperature acceleration method suggested bythe literature. All specimens were subjected to 11 hours in a dry ovenat 177° C. and then placed in a saline water bath for 46 days at 87° C.This subjected the specimens to 24 years equivalent worth of aging. Ithas been suggested that an increase of 10 degrees C. doubles the agingprocess. Therefore placing the samples to the above heating conditionswill be equivalent to at least 24 years worth of aging.

Specimens were glued to the test platens and left to dry for 24 hours.The specimens and test platens were then connected to thespinesimulator. The test stain was filled with calf serum and maintainedat 37±3° C.

The test execution was as follows: —

1) A compression load of 100N and 600N was applied and the heights ofthe specimens at these loads were measured. This height was taken as thereference heights

2) Specimens were cyclically loaded under the following conditions:—

-   -   Compression        -   Load range:            -   600N to 2000N for 10 000 cycles            -   600N to 1500N for 990 000 cycles        -   Load frequency: 2 Hz    -   Flexion/Extension        -   Bending range: +6/−3°        -   Range frequency: 1 Hz    -   Lateral Bending        -   Bending Range: ±2°        -   Range frequency: 1 Hz    -   Axial Rotation        -   Bending Range: ±2°        -   Range frequency: 1 Hz

3) After the completion of the 1 million compression cycles a 100N and600N load was reapplied to measure the height change.

All specimens were loaded to 100N and 600N and the heights measured atthis load. After the specimens were subjected to cyclic load the 100Nand 600N load was reapplied to measure the heights. These values werecompared to the reference heights.

Height loss at 100N Height loss at 600N Specimen reference loadreference load 3.1 0.53 1.4 3.2 0.49 1.3 3.3 0.44 1.3 3.4 0.45 1.1 3.50.55 1.3 3.6 0.46 1.2 Mean 0.49 1.3 Std. dev. 0.1 0.1

The average height loss at the 100N and 600N reference loads was 0.49 mmand 1.3 mm, respectively. The height measurements after 1 million cyclesshowed the aged specimens performed better than the fatigue specimens interms of height loss.

No cracks were observed on any of the specimens and aging does not haveany serious adverse mechanical effects on the implant.

Height maintenance is an important mechanical function in a nucleusreplacement device. This test aims to evaluate the dynamic fatigueproperties of the implant constrained within an artificial annulusmodel.

The filler material (CSM-2186-14) was injected into the annulus cavityvia a 4 mm annulotomy and left to cure for 24 hours.

Specimen was placed between the two test platens.

2) Specimens were subjected to a 509N compressive load to reduce thecreep affects.

3) The specimen was then subjected to a cyclic compression loadingbetween 509N and 1730N at 2 Hz for 100,000 cycles.

The change in peak height during the cyclic loading and the change inheight during the cyclic loading was measured.

The maximum and minimum height (at 509N and 1730N load respectively) ofthe samples was recorded for the predetermined cycles. A reduction inheight during the 1 million cycles (dynamic creep) was evident in bothsamples where the greatest observable difference was recorded betweencycles 1 and 5,000. The rate of height loss (dynamic creep) plateaus outbetween cycles 5,000 to 100,000.

Cycling the specimens between 509N (0.5 MPa) and 1730N (1.7 MPa) isapproximately equivalent to a person standing in a relaxed position toand lifting a 20 kg. Cycling the implant in this fashion is thus a grossover-exaggeration of what a person would encounter in everyday lifehowever the aim was to test the lifecycle of the device in a worst casescenario at accelerated loading conditions and thus justified.

The dynamic creep of the implant constrained within an annulus modelover 100,000 cycles was, less than 5%.

A finite element analysis of the implant was also performed, and thefollowing items were observed from the model.

The implant is believed to restore the nucleotomy model tonear-physiological axial displacement when the implant completely fillsthe nucleotomy volume. Data indicates that the implant axialdisplacement approaches the result provided by the intact model. Incontrast to this, the untreated nucleotomy results in an abnormally lowaxial stiffness.

The extent of the nucleotomy relative to the nucleus volume does nothave as pronounced effect on the axial stiffness when compared to theextent the implant fills the nucleotomy. This is apparent when theimplant model (based on a finite element analysis) (100% filling ofnucleotomy) is compared with the partial implant (see, FIG. 86). Thepartial implants and new inflation models (30%, 70%) do not showsignificant difference between each other. This phenomenon relies on theassumption that a void remains between the implant and the nucleotomy inthe partial-fill implant.

In reference to FIGS. 3-7, when the nucleus pulposus 18N has beenremoved, a residue 64R remains about the inner surface of the annulusfibrosis and on the end plates 20E of the vertebrae 12V and 14V. Thisresidue 64R is of an irregular shape. Therefore, in charging theenvelope 38E with the filler material 60F, it is necessary to monitorthe charging of the filler material 60F into the envelope 38E. This isdone by a sensing arrangement. In one embodiment, the sensingarrangement comprises a pressure sensor 66PR at an inlet to the envelope38E. In another embodiment, the sensing arrangement comprises a volumesensor 68S arranged at an outlet of the dispenser 62D for monitoring thevolume of filler material 60F dispensed. The sensing arrangement could,in addition or instead, be a flow rate sensor which monitors the rate offlow of the filler material 60F.

Yet a further method of monitoring filling of the envelope 38E ismonitoring back flow of filler material 60F from between the envelope38E and the distal end of the tubular delivery device 40T. As the fillermaterial 60F oozes out it may loosen the envelope 38E allowing thetubular delivery device 40T to be removed.

In FIGS. 43-76, reference numeral 10I generally designates anintervertebral disc implant in accordance with various embodiments. Theimplant 10I comprises an envelope 12E in which a filler material 14FM isreceived. The implant 10I is intended for use in replacing a nucleuspulposus of an intervertebral disc 16I arranged between adjacentvertebrae 18A, 20A. Generally, the procedure is formed in a minimallyinvasive manner as will be described in greater detail below. It willalso be appreciated that the procedure may be conducted in apercutaneous manner as described herein and in greater detail below.

It will be appreciated that the disc 16I comprises an annulus 22Acircumscribing a nucleus pulposus. The intervertebral disc implant 10Iis intended to replace a degenerate nucleus pulposus of the disc 16I.Thus, the implant 10I is implanted after the disc 16I has undergone anucleotomy to remove the nucleus pulposus.

In the embodiments illustrated in FIGS. 43 to 53, the envelope 12E ofthe implant 10I is of a stretchable and elastically deformableelastomeric material such as a silicone material. Various fillermaterials 14FM can be used with the envelope 12E in order to mimic asclosely as possible the biomechanical actions of a natural, healthynucleus pulposus.

In the embodiment shown in FIGS. 43a, 43b and 43c , the filler material14FM comprises beads 24B held in suspension in a curable elastomericmaterial. The elastomeric material is, once again, preferably a siliconematerial.

The beads 24B are of a biocompatible material. Thus, for example, thebeads 24B could be of a suitable biocompatible plastics material, abiocompatible elastorneric material, a biocompatible metal material, abiocompatible ceramic material or suitable biological material such asproteoglycans. The beads 24B may be homogenous in the sense that all thebeads are of the same size and same material. Instead, the beads 24B maybe of different sizes and different materials in order to obtainparticular biomechanical characteristics for the implant 10I.

In certain embodiments, the beads need not be spherical in shape. Theycould, instead, be any one of bullet shaped, polygonal, triangular,heart shaped, kidney shaped, ovoid, oblong, crescent shaped, cubic,elongated, conical, trapezoidal, prismatic irregular, or combinationsthereof. In some aspects, a preferred shape is one which allows forconvenient and unobstructed insertion. Thus, preferably, the beads 24Bhave radius-like corners and/or edges to minimize the risk of damagingthe envelope 12E.

The beads 24B may range in size from 0.01 mm to 5 mm and, optimally, anysize in order that the beads 24B can be introduced into the interior ofthe envelope 12E by an introducer.

In the embodiment shown in FIGS. 44a, 44b and 44c , the filler material14FM comprises elongate, filamentary elements 28F carried in suspensionin the silicone. The filamentary elements 28F are “string-like” elementswhich are, once again, of suitable biocompatible materials. The elements28F typically have lengths not exceeding 1 cm. Once again, the lengthsof the filamentary elements 28F may all be the same or they may differto obtain the desired biomechanical characteristics for the implant 10I.

In FIGS. 45a, 45b and 45c , the filler material 14FM comprises fibres30F in suspension in the silicone. The fibres 30F are, typically, oflengths less than 3 mm. As in the case of other disclosed embodiments,the fibres 30F are made up of suitable biocompatible materials. Thefibres 30F are selected either to all be of substantially the samematerial and lengths or they may be of different materials and ofdifferent lengths to obtain the desired biomechanical characteristicsfor the implant 10I.

FIGS. 46a, 46b and 46c illustrate certain embodiments in which thefiller material 14FM comprises spherical elements contained in theenvelope 12E. The spherical elements 32S are of suitable biocompatiblematerials such as biocompatible plastics, biocompatible elastomers,biocompatible metals, biocompatible ceramics or biological material. Thespherical objects may be in a range of sizes not exceeding 3 mm to 4.5mm (e.g., not exceeding 3, 3.25, 3.5, 3.75, 4, 4.25, 4.5, etc.) in orderto be able to be introduced into the interior of the envelope 12E via anintroducer as will be described in greater detail below.

The spherical elements 32S are typically provided in a range of sizes toprovide compacted packing of the filler material 14FM within theinterior of the envelope 12E but still allowing compressive stresses onthe disc 16I to be transmitted to the annulus 22A of the disc.

In FIGS. 47a, 47b and 47c , the filler material 14FM comprises one ormore lengths of string-like elements 34S. Each element 34S may typicallyhave a length less than 10 cm and a diameter less than 3.5 mm to 4 mm.Sufficient lengths of elements 34S are provided to pack the interior ofthe envelope 12E to provide the necessary weight bearing functions ofthe implant 10I. These elements 34S are, once again, of biocompatiblematerial.

Referring now to FIGS. 48a, 48b and 48c , the filler material 14FMcomprises a plurality of short lengths of fibre 36S. The fibres 36S are,typically, about 2 to 3 mm long and are of biocompatible materials. Thefibres 36S are packed into the interior of the envelope in a compactedstate in order to impart the required biomechanical characteristics tothe implant 10I. Once again, the fibres 36S may be of differentmaterials and different lengths.

In FIGS. 49a, 49b and 49c , the filler material 14FM comprises aplurality of bottlebrush-like elements 38B. The bottlebrush elements 38Bare of the form having a central spine with bristles projecting radiallyoutwardly from the spine. The bristles are folded on to the spine forintroduction into the envelope 12E via an introducer.

Once again, the bottlebrush elements 38B are packed, in a compactedstate, within an interior of the envelope 12E to impart the necessarybiomechanical characteristics to the implant 10I. The bottlebrushelements 38B may be of biocompatible plastics materials. In addition,the bottlebrush elements 38B may be in the form of biocompatiblemetals/biocompatible plastics combinations. An example of this would bea bottlebrush elements 38B having a metal spine with plastics bristles.Still further, the bottlebrush elements 38B could be of all metalconstruction. The elements 38B typically have a length of less thanabout 1 cm, preferably about 5 mm. When the bristles are folded on tothe spine for insertion into the introducer, the elements 38B may have adiameter not greater than about 3.5 mm to 4 mm.

Once again, if desired, bottlebrush elements of mixed sizes andmaterials may be used together to mpart the desired biomechanicalcharacteristics to the implant 10I.

Referring now to FIGS. 50a, 50b and 50c , the filler material 14FMcomprises lengths of helical or coiled wires 40W. The coiled wires 40Ware packed, to be in a compacted state, in the interior of the envelope12E in order to provide the necessary biomechanical characteristics. Thecoiled wires, in their relaxed state, may typically be less than about 1cm in length, preferably, about 5 mm in length. The wires 40W may be ofbiocompatible plastics, biocompatible elastomers, or biocompatiblemetals. As in the previous embodiments, wires 40W of different lengthsand different materials may be used together, if desired, in the implant10I.

In the embodiment shown in FIGS. 51a, 51b and 51c , the filler material14FM comprises a plurality of discrete bands 42D of a resilientlyflexible, biocompatible material arranged concentrically within theenvelope 12E to form the implant 10I. The bands 42D have a thickness notexceeding about 1 mm and a height not exceeding of about 9 mm.

The filler material 14FM in the embodiments illustrated in FIGS. 52a,52b and 52c are made from a foamed material 44F. The foamed material 44Fis introduced, in a compressed state, via the introducer into theinterior of the envelope 12E. Once the introducer is withdrawn, thefoamed material 44F expands to a relaxed state to cause the envelope 12Eto conform to the volume in which it is placed. Typically, the foamedmaterial 44F is a polymeric material such as a polyethylene.

In FIGS. 53a, 53b and 53c , the filler material 14FM is silicone oil46SI, having a viscosity of at least 500 cP. This material exhibitssurprisingly good biomechanical characteristics and mimics closely anatural, healthy nucleus pulposus of an intervertebral disc.

In the embodiments described above, as previously described, theenvelope 12E is generally of a silicone material which has an elongationof up to 1000%. where it can expand elastically without plasticallydeforming. In certain circumstances, it may not be necessary to have theenvelope have such extensive elongation and, if desired, the envelopecould be made of other materials in appropriate circumstances, such as,for example, woven metal fibres such as stainless steel, nitinol, chromecobalt, titanium, or the like; or combinations thereof. Instead, theenvelope may be of a plastics material such as a polymeric material likepolytetrafluoroethylene.

Further, in the embodiments described above, the implant 10I makes useof an envelope. In certain circumstances, the implant 10I may notrequire an envelope 12E. In the embodiments illustrated in FIGS. 54 and55, the implant 10I comprises an elongate element 48E of a suitableresiliently flexible material, such as a silicone material. In thisembodiment, the element 48E is inserted into the volume resulting afterthe nucleotomy has been performed on the disc 16I in an elongated stateas shown in FIG. 54 of the drawings. Use of a stylet 50S maintains theelongate element in its extended state. When the elongate element 48E isinserted into the volume, the stylet 50S is withdrawn causing theelongate element 48E to adopt the configuration shown in FIG. 55 inwhich the element 48E substantially fills the volume. In a similarembodiment to this, a plurality of such elements 48E are used, eitherside by side or one on top of the other in layers, to conform to thevolume. In the latter case, the elements 48E may, if desired, beinserted into an envelope (not shown).

FIGS. 56 and 57 show a similar embodiment of implant 10I in which theimplant 10I comprises a plurality of doughnut-like members 52Minterconnected serially to form an implantable element 54I. Once again,the implantable element 54I has a stylet 56STY associated with it to aidimplantation.

In a relaxed state, the implantable element 54I adopts the configurationshown in FIG. 57. The implantable element 54I is implanted, in its firstconfiguration, as shown in FIG. 56, into the volume of the disc 16I.Withdrawal of the stylet 56STY causes the implantable element 54I to becompressed, as shown in FIG. 57, into a second configuration in which itconforms substantially to the volume of the disc 16I.

Once again, in a similar manner to the embodiment described above withreference to FIGS. 54 and 55, a plurality of the implantable elements54I may be used, either side by side or in layers to conform to thevolume of the disc 16I. In this case, the implantable elements 54I maybe received in an envelope (not shown).

Referring now to FIGS. 58 and 59, yet a further embodiment of an implant10I is illustrated.

In this embodiment, the implant 10I for an intervertebral disc 20Igenerally comprises an elongate implantable element 58I which,optionally, has a stiffening spine 60S. The implantable element 58I is,typically, an elastomeric material such as, for example, silicone. Thespine 60S is of a shape forming material or shape memory alloy such asnitinol.

The implantable element 58I is inserted via an introducer into thevolume of the disc 16I. One or more lengths of the implantable element58I may be used to cause the implantable element 58I to conform to theshape of the volume in order to function as a replacement nucleuspulposus of the disc 16I.

In FIG. 60, an embodiment similar to that described above with referenceto FIGS. 58 and 59 is illustrated. In this embodiment, the implant 10Ifor an intervertebral disc 20I generally comprises two, coiledimplantable elements. Each implantable element 62I has a coiled shapedin its relaxed state. This coiled shape may be imparted by a stiffeningspine of shape forming alloy such as nitinol (not shown). Instead, theimplantable elements 62I may be formed in such a manner that, in theirrelaxed state, they adopt a coiled configuration.

In this embodiment, the implantable elements 62I are straightened forintroduction into the volume of the disc 16I. Once in the volume, theimplantable elements 62I coil in oppositely directed orientationssubstantially to fill the volume resulting from removal of the originalnucleus pulposus of the disc 16I.

In FIGS. 61 and 62, the implant 10I comprises a single, implantableelement 64I. The implantable element 64I is of an elastomeric material,such as silicone, and, in its relaxed states, is in a shape which willsubstantially conform to the volume of the disc into which the element64I is to be imparted.

To aid in implantation of the element 64I, a plurality of cuts 66C aremade in the element. These cuts 66C cause “hinges” 68H to be formedabout which the parts of the element on either side of the cut 66C canhinge to straighten the element 64I to be implanted via an introducerinto the vacated volume of the disc 16I.

The embodiments of the implants shown in FIGS. 63 and 64 are similar tothose shown in FIGS. 61 and 62. In the embodiment shown in FIG. 63 ofthe drawings, the implant 10I comprises a single implantable element 70Iformed into a snake-like configuration, in its relaxed state. Theimplantable element 70I has a convex profile. The embodiment shown inFIG. 64 of the drawings is of a similar form with the distinction thatan implantable element 72I of the implant 10I of the embodiment shown inFIG. 64 has a concave profile. Once again, in both embodiments, theimplantable element 70I, 72I is extended into a straight configurationfor implantation via an introducer. Once in the volume of the disc 16I,the implantable element 70I, 72I adopts its relaxed, illustratedconfiguration substantially to conform to the volume of the disc 16I.

Yet a further embodiment of an implant 10I is shown in FIGS. 65-67. Onceagain, with reference to the previous embodiments, like referencenumerals refer to like parts, unless otherwise specified.

In this embodiment, an attaching formation 74A of the envelope 12E isshown. It is to be understood that the envelope 12E of each of theembodiments described above also includes such an attaching formation.The attaching formation 74A is used for attaching the envelope to anintroducer 76I (FIG. 74). The attaching formation 74A is in the form ofa filler tube. The filler tube 74A, in this embodiment, extends radiallyoutwardly from the body of the envelope 12E. A closure device in theform of a duck-billed valve 78V is arranged at a distal end of thefiller tube 74A. When the introducer 76I is inserted into the fillertube 74A, it causes the valve 78V to open. Withdrawal of the introducer76I from the filler tube 74A causes the valve 78V to close.

In this embodiment, the envelope 12E has an annular region 80A of areasonably rigid material. The material of the annular region 80A ismore rigid than material forming upper member 86M and lower member 82Mof a central part of the envelope 12E. The annular region 80A of theenvelope 12E, bears against the annulus 22A of the disc 16I, in use.When the filler material 14FM is charged into the interior of theenvelope 12E, the members 82M and 86M expand outwardly as shown by theupper member 86M in FIG. 66 of the drawings to bear against thevertebrae 18A, 20A and so cause the envelope 12E to conformsubstantially to the volume of the disc 16I.

It is to be noted that both members 82M and 86M carry, on their outersurfaces, a layer of tissue ingrowth material 84M. The material 84M is,typically, a polyester material such as that sold under the registeredtrade mark Dacron.

The annular region 80A is of a substantially non-stretchable materialwhile the members 82M and 84M are made to stretch and expand in volume.The material of the annular region 80A is still sufficiently flexible toenable the envelope 12E to be collapsed to be inserted via an introducerinto the vacated volume of the disc 16I.

FIGS. 68-73 show various embodiments of a multi-chambered envelope 12E.As shown in FIG. 69, the envelope 12E has a plurality of chambers 86C,each of which is fed by a collapsible delivery tube 88D. Each deliverytube 88D has a valve (not shown) at its distal end. Filler material isintroduced into each of the chambers 86C of the envelope 12E via theassociated delivery tube 88D. Thus, filling of each of the chambers 86Ccan occur independently. In addition, the filler material received ineach chamber 86C may differ from the filler material received in anyother chamber 86C. Still further, certain of the chambers 86C may, incertain circumstances, not have any filler material at all.

A sample of the construction of the envelope 12E is shown in FIGS.71-73. The envelope 12E has an upper member 90U and a lower member 92Linterconnected by a sidewall 94S. A plurality of partitions 96P extendin the interior of the envelope 12E between the upper member 90U and thelower member 92L. The partitions 96P are configured to have strongcompressive load bearing capabilities but to collapse in shear as shownin FIG. 73 of the drawings. Thus, for introduction of the envelope intothe vacated volume of the disc 16I, the partitions 96P are collapsed, asshown in FIG. 73 by moving the members 90U and 92L laterally relative toeach other.

It will be appreciated that various other configurations ofmulti-chambered envelopes 12E can be formed by using different materialsfor different chambers of the envelope and/or filling the variouschambers with different filler materials 14FM, as described above.

In FIGS. 74 and 75, a system, in accordance with another embodiment, forimplanting an intervertebral disc implant is shown and is illustratedgenerally by the reference numeral 100S. The system 100S comprises theimplant 10I and an introducer 76I. The introducer 76I has an elongatetubular element 102E on a distal end of which is received the attachingformation 74A of the envelope 12E. A non-return valve 78V is arranged ata distal end of the attaching formation 74A. In the embodimentillustrated in FIGS. 74 and 75, the filler material comprises the balls32B of the embodiment described above with reference to FIGS. 46a, 46band 46 c.

The annulus 22A of the disc 16I is accessed percutaneously in a patientand an opening is made through the annulus 22A. The degenerate nucleuspulposus is removed using ablation, lasers or mechanical means to createa vacated volume. The introducer 76I with the envelope 12E in acollapsed configuration on the distal end of the tubular member 102E isinserted through the incision so that the envelope 12E is within thevolume of the disc 16I.

Filler material 14FM is fed through the tubular member 102E of theintroducer 76I into the interior of the envelope 12E to cause theenvelope 12E to expand to conform to the volume of the disc 16I. In theembodiment shown in FIGS. 74 and 75, the filler material is fed throughthe introducer 76I via an appropriate displacement mechanism, such as apump (not shown). Once the envelope 12E has expanded to conform to thevolume, charging of filler material 14FM into the interior of theenvelope 12E ceases. The tubular member 102E of the introducer 76I iswithdrawn from the attaching formation 74A of the envelope 12E.Withdrawal of the tubular member 102E causes the value 78V to closeinhibiting leakage of the filler material 14FM from within the envelope12E.

It will be appreciated that the balls 32B have been shown merely as oneexample of the type of material 14FM used with the introducer 76I. Otherfiller materials having discrete elements are also able to be injectedinto the envelope 12E of the implant 10I using the introducer 76I.

In FIG. 76, part of another embodiment of an introducer is illustrated.In this embodiment, the displacement mechanism for charging fillermaterial 14FM into the interior of the envelope 12E comprises adisplaceable element 104D. The displaceable element 104D is a sleevereceived within the tubular member 102E of the introducer 76I and whichis able to reciprocate relative to the tubular member 102E. An innersurface of the sleeve 104D carries a ratchet arrangement 106R. Byreciprocating the sleeve 104D relative to the tubular member 102E fillermaterial 14FM can be fed along the introducer 76I into the interior ofthe envelope 12E by means of the ratchet arrangement. The introducer 76Iof the embodiment shown in FIG. 76 of the drawings is useful forintroducing elongate elements into the interior of the envelope or, incertain circumstances, such as the embodiments shown in FIGS. 54-64directly into the volume where no envelope is used. An example of animplant 10I which would use the introducer 76I of the embodiment of FIG.76 is that shown in FIGS. 47a, 47b and 47c as well as the embodimentshown in FIGS. 51a, 51b and 51 c.

It is to be noted that the implant 10I may be used to deliver bioactivesubstances to the annulus 22A of the intervertebral disc 16I. Thebioactive substances may be substances which induce cell growth and/orcell reproduction. Further, the implant 10I may be used as a drugdelivery means for active and/or prophylactic treatment at the site ofimplantation. Substances to be delivered may include may include genetelomerase, proteins, cells, autologous chondrocytes and autologous bonemarrow derived mesenchymal stem cells.

Hence, it is an advantage of certain embodiments, that an intervertebraldisc implant is provided which can mimic the biomechanicalcharacteristics of a natural, healthy nucleus fibrosis of anintervertebral disc. It is a particular advantage of certain embodimentsthat an implant and system are provided which enables the implant to beinserted in a minimally invasive manner thereby obviating the need fordrastic surgery. By use of discrete elements for the filler material14FM, the biomechanical properties of the implant 10I can be tailored toparticular requirements as desired by a clinician.

The disc is a highly viscoelastic structure and this makes it a veryefficient and effective shock absorbing unit. In a healthy disc, the NPis well hydrated with a very gel like consistency and under the variousmodes of loading, the NP is pressurised and deformed, directing theincident load radially onto the AF and end plates. This creates anintradiscal pressure and load transfer between adjacent vertebrae isfacilitated as the AF fibers are maintained in tension from the hoopstresses which result from the intradiscal pressure. This cooperativemechanism between the NP and AF provides the disc with the ability tosustain compressive loads retain the separation required between theadjacent vertebrae and provides controlled movement. With the onset ofdisc degeneration, brought upon by age or injury, there is a disruptionin the balance between the NP and AF resulting in a destabilization ofthe motion segment. Common parameters which are used to evaluate themobility and stability of the motion segment are neutral zone (NZ) andrange of motion (ROM). In disc degeneration, the NZ (or joint laxity)increases along with its ROM. As the disc degenerates and becomesdehydrated, the NP shrinks and the ability to act as a shock absorbing,energy dissipating mechanism is compromised. A shrinkage in the NPresults in a loss in the intradiscal pressure which then alters thestress distribution through the disc and since the intradiscal pressureis lost, the hoop stresses are lost also. Without the hoop stresses, theannulus is not able to be maintained in a taught orientation, eventuallyleading to delamination and shearing of the annular layers. The loss inintradiscal pressure also creates an increased laxity in the joint andan increase in the joint laxity means that there is a greater range ofmotion from the neutral position that is unsupported and unresisted,indicating an increased level of instability in the segment, adding morestress on the posterior articulating elements and adjacent segments tosustain the loads.

As it can be shown in the kangaroo motion segment study, by implanting anucleus prosthesis, more specifically, one of the prostheses disclosedherein into a degenerate disc or at least a nucleotomised disc, the NZand ROM of the motion segment is capable of being restored to that of anintact disc.

Specifically, the objectives of this study were to evaluate thebiomechanical properties of the device using a cadaveric kangaroo lumbarspine model. The specific research question was whether kinematicvariables differ when treating a motion segment with nucleotomy ornucleotomy then implantation with the exemplary device?

Ten kangaroo spine lumbar motion segments (L3/L4 and L5/L6) with allmusculature, ligamentous tissue and posterior elements removed wereseparated into two equal groups. All specimens were tested in an intactstate (pretreatment) prior to undergoing either a nucleotomy(nucleotomy) or undergoing a nucleotomy with implantation of aconformable elastomeric NR device (such as the devices disclosed herein)and then retested. All samples where tested in lateral bending andflexion-extension on a custom built jig attached and tested at 3.4deg/sec with loads of −1.4 Nm to 1.4 Nm. Kinematic data were collatedfrom the load displacement curve included; Neutral Zone (NZ), Range ofmotion (ROM), and Hysteresis. NZ is defined as the range which thespecimen displaces with zero loads; ROM is defined as range from thestart position to the point of maximal displacement in a givendirection; and Hysteresis is defined as the energy difference betweenloading and unloading cycles on a stress-strain curve.

Before and after treatment analysis was performed using the StudentPaired t-test with alpha set at 0.05. Results were presented as medianpercentage change compared with control with 95% confidence intervalsfor difference of means.

In flexion-extension the ROM of the nucleotomy and implant groupincreased by 24% (CI 5% to 65%) and 12% (CI −6% to 30%) respectivelywhen compared to pretreatment. The NZ in the nucleotomy and implantgroup increased by 124% (CI 20% to 202%) and 0.5% (CI 7% to 31%)respectively when compared to pretreatment. In lateral bending, the ROMof the nucleotomy and implant group increased by 35% (CI 6% to 72%) and5% (CI −22% to 42%) respectively when compared to pretreatment. The NZin the nucleotomy and implant group increased by 69.8% (25% to 256%) and0.5% (CI −28% to 33%) respectively when compared to pretreatment.

Accordingly, in this study, there was an increase in motion segmentlaxity after nucleotomy during sagital and coronal movements offlexion-extension and lateral bending, which is reversed withimplantation of the exemplary device. The data suggests that theexemplary device can restore the biomechanical changes in a de-nucleatedmotion segment.

Additionally, an embodiment of the implant disclosed herein wasimplanted into a 41 year old male who presented with lower back pain for4.5 years following a work related injury in 2003. He subsequentlyunderwent a posterior decompression surgery in 2005 which resulted inrelief of pain for a brief time but then continued to complain of backpain which he rates at 9 out of 10 and bilateral leg pain. He hadsignificant restriction of all activities of daily living and was takinghigh doses of narcotic analgesics to control his pain. He has no othermedical co-morbidities nor does he have any ongoing legal issues relatedto his work injury. A physical examination revealed a cooperative,pleasant gentleman who overall has good balance and station. Themovements of the thoracolumbar spine were painful and grossly restrictedin the sagittal plane. Lower limb neurology was nearly normal. Thestraight leg raising test was positive on the right side.

An MRI scan of the LS spine showed degeneration of the L4-L5 disc. Theadjacent discs appeared to be well hydrated. Radiographs of thelumbo-sacral spine showed normal alignment. The patient had no relief ofsymptoms following a whole range of non-operative treatment modalities,including physiotherapy and spinal injections. He was eventuallyconsidered for the procedure disclosed herein.

He underwent a partial nucleus replacement procedure on 27 Dec. 2007 andthe immediate post-operative period was uneventful. At the six week markafter surgery, the patient had about an 80% reductionin his back painand about a 90% reduction in his leg pain. He is presently undergoingphysiotherapy to increase his activity levels and the narcoticanalgesics are being tapered. The short term results have been veryencouraging.

In one of the embodiments, a polymeric material, more specifically anelastomer, and preferably a silicone, of a particular hardness is usedfor a nucleus prosthesis. The hardness of the material may be in therange of 1-20 A or 21-40 A or 41-60 A or 61-80 A or greater than 81 AShore Hardness, but preferably about 25 A. Materials like silicones arewell suited for a nucleus prosthesis application because it is aviscoelastic material which means it is capable of providing the shockabsorbing requirements of the motion segment. Under a given load, theprosthesis deforms and is capable of distributing the applied loadradially to evenly distribute the load across the endplate and to theannulus. This reduces the risk of the implant subsiding into theendplates and restores the intradiscal pressure which restores the hoopstresses to the annulus. More importantly, the nucleus prosthesis iselastically deformable. Thus, the application of force will cause thenucleus prosthesis to deform elastically so that, once the force hasbeen removed, the prosthesis will return to its relaxed, undeformedstate.

Therefore, some beneficial characteristics of the implant disclosedherein may include, for example, shock absorption, restore hoopstresses, provide required range of motion, restore biomechanics, withinthe required range of hardness (shore hardness) (less chance of implantsubsidence), using same class of materials results in homogeneity, fastcuring, substantially biocompatible, in mild to moderate discdegeneration the implant is not only load distributing but also loadbearing, substantially silicone, silicone composites, polyurethane,cellulose, collagen based, elastin based.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the inventions as shownin the embodiments without departing from the spirit or scope of theinventions as broadly described. The present embodiments are, therefore,to be considered in all respects as illustrative and not restrictive.

We claim:
 1. A self-contained closed implant system for the formation ofa prosthesis device percutaneously within a nucleus cavity formed in anintervertebral disc at an in situ implant site, comprising: a singlelumen working cannula, said single lumen working cannula configured tobe docked against an outer surface area of an annulus surrounding thenucleus cavity, wherein said single lumen working cannula has arrangedat about its proximal end a collar assembly to facilitate matinglyengaging the single lumen working cannula with said closed insertionassembly; a closed sizing assembly configured to be partially receivedwithin said single lumen working cannula for carrying at a distal endthereof an elastically deformable mock implant member to the in situimplant site to facilitate determining, without fluid evacuation fromthe closed implant system, a known volume of filler material tosubstantially fill the volume of the nucleus cavity; a closed insertionassembly configured to be partially received within said single lumenworking cannula in place and stead of said closed sizing assembly forprotectively carrying an elastically deformable implant member to the insitu implant site to facilitate its filling with said known volume offiller material; a closed dispensing assembly configured to be partiallyreceived within said single lumen working cannula and removably coupledto said closed insertion assembly without relative rotational motiontherebetween to facilitate the filling of the elastically deformableimplant member with said known volume of filler material without fluidevacuation from the closed implant system; and wherein the closeddispensing assembly includes a distal end magnetic mount for removablycoupling the closed dispensing assembly to the single lumen workingcannula and a proximal end magnetic mount for removably coupling theclosed dispensing assembly to the closed sizing assembly to facilitatedetermining, without fluid evacuation from the closed implant stem theknown volume of filler material to substantially fill the volume of thenucleus cavity and for removably coupling the dispensing assembly to theclosed insertion assembly in place and stead of the closed sizingassembly to facilitate the filling of the elastically deformable implantmember with the known volume of filler material without fluid evacuationfrom the closed implant system to help reduce tissue trauma to a patientby obviating relative rotational coupling motions.
 2. The self-containedclosed implant system according to claim 1, wherein said closed sizingassembly includes: a tube having a single lumen for carrying the mockimplant member at a distal end thereof; a connector coupled at aproximal end of said tube, said connector defining a primary lumen forfluid communication with said tube and a secondary lumen for fluidcommunication with said tube; at least one pressure transducer coupledfluid dispenser arrangement including a primary syringe connectable tothe primary lumen for fluid communication with said single tube and asecondary syringe connectable to the secondary lumen for fluidcommunication with said single tube; a fluid control arrangementdisposed at a proximal end area of said single tube operable to placeeither the primary lumen of the connector in fluid communication withthe tube or secondary lumen of the connector in fluid communication withthe tube; wherein said primary syringe is connectable to said connectorto be in fluid communication with said primary lumen, said primarysyringe having a barrel and a plunger slidably displaceable in thebarrel to facilitate the delivery and removal of a non-compressibleliquid to the mock implant member; wherein said secondary syringe isconnectable to said connector to be in fluid communication with saidsecondary lumen, said secondary syringe having another barrel andanother plunger slidably displaceable in said another barrel tofacilitate the delivery and removal of a compressible liquid to the mockimplant member; wherein said fluid control arrangement is operable in apriming step to occlude, the fluid communication path between saidprimary lumen and the tube and to open the fluid communication pathbetween said secondary lumen and the tube to facilitate inflating saidmock implant member with compressible liquid dispensed from saidsecondary syringe and compressible liquid contained within the closeddelivery system; and wherein said fluid control arrangement is operablein another priming step to occlude the fluid communication path betweensaid secondary lumen and the tube and open the communication pathbetween said primary lumen and the tube to facilitate placing saidprimary syringe in fluid communication with said tube for inflating themock implant member with non-compressible liquid dispensed from saidprimary syringe, said primary syringe containing a sufficient volume ofthe non-compressible liquid to inflate said mock implant member to afully expanded state conforming to the shape of the nucleus cavity toprovide an indication of said known volume of filler material tosubstantially fill the volume of the nucleus cavity.
 3. Theself-contained closed implant system according to claim 2, wherein thenon-compressible fluid dispensed from said primary syringe is heavierthat the compressible fluid dispensed from said secondary syringe;wherein said heavier non-compressible fluid sinks to a distal endportion of the mock implant member; and wherein the compressible fluidcontained within the closed implant system collects at about a distalend of the tube.
 4. The self-contained closed implant system accordingto claim 3, wherein said mock implant member, in its fully collapsedprimed state, points upwardly since the buoyancy of the compressiblefluid within the closed sizing assembly causes the compressible fluidtherein to disperse toward a distal portion of said mock implant memberin close proximity to the single lumen of said tube; and wherein saidmock implant member, in its fully inflated state, points downwardlyduring said priming step to facilitate an accurate measurement of thenucleus cavity.
 5. The self-contained closed implant system according toclaim 4, wherein withdrawal displacement of said another plunger withinsaid another barrel is prevented in the closed sizing assembly fromextending beyond a zeroing position when said mock implant member is insaid fully collapsed state and is extendable in an opposite displacementuntil a sudden increase in pressure resulting from the mock implantmember becoming fully inflated with a sufficient volume ofnon-compressible liquid so the mock implant member substantiallyconforms to the shape of the nucleus cavity.
 6. The self-containedclosed implant system according to claim 5, wherein said sudden increasein pressure causes a transducer coupled to the plunger of said primarysyringe to emit an enunciation.
 7. The self-contained closed implantsystem according to claim 6, wherein said enunciation is an audibleenunciation indicative of an end point in filling the mock implantmember with the non-compressible fluid.
 8. The self-contained closedimplant system according to claim 6, wherein said enunciation is avisible enunciation indicative of n end point in filling the mockimplant member with the non-compressible fluid.
 9. The self-containedclosed implant system according to claim 1, wherein said closeddispensing assembly includes: a connector in fluid communication withthe elastically deformable implant member; a withdrawing device in fluidcommunication with said connector for increasing the volume of theclosed implant system to facilitate collapsing the elasticallydeformable implant member and removing substantially all fluidstherefrom so said elastically deformable implant member may be filedwith said know volume of filler material without fluid evacuation fromthe closed implant system; and a dispensing device in fluidcommunication with said connector for dispensing to collapsedelastically deformable implant member said known volume of fillermaterial without fluid evacuation from the closed implant system. 10.The self-contained closed implant system according to claim 9, whereinsaid closed dispensing assembly further includes a sensing arrangementfor providing an indication that the elastically deformable implantmember has been inflated with a sufficient volume of filler materialcorresponding to said known volume of filler material; wherein upon saidsensing arrangement providing said indication, said dispensing assemblymay be immediately removed from the working cannula without waiting forthe filler material in the elastically deformable implant member tocure.
 11. The self-contained closed implant system according to claim10, wherein said dispensing assembly still further includes an occludingarrangement for occluding access to the inflated elastically deformableimplant member concurrently with the immediate removal of saiddispensing assembly.
 12. The self-contained closed implant systemaccording to claim 1, said collar assembly including: a cannula collarsecured at a proximal end of said single lumen working, cannula; saidcannula collar having a set of recesses to help facilitate the removalof a protective sheath surrounding the implant member once it is placedwithin nucleus cavity; a push-off collar removably secured to a proximalend of said cannula collar to help facilitate separating the implantmember from the closed implant system; a connector collar removablysecured to a proximal end of said push-off collar for coupling saidclosed insertion assembly to said closed dispensing assembly withoutrelative rotational motion therebetween to facilitate the filling of theimplant member with said known volume of filler material without fluidevacuation from the closed implant system; and wherein said single lumenworking cannula is configured with a pair of oppositely disposedlongitudinally extending slits dimensioned for slidably receivingtherein a set of tabs extending outwardly from said protective sheath,said tabs being dimensioned to be received within the set of recessesdisposed in said cannula collar to further help facilitate the removalof the protective sheath from the implant member once the implant memberis placed within the nucleus cavity.
 13. The self-contained closedimplant system according to claim 1, wherein said closed insertionassembly includes: a single lumen carrier tube for carrying at a distalend thereof the elastically deformable implant member; a protectivesheath extending over the elastically deformable implant member forprotecting it while being carried and placed within the nucleus cavityby said single lumen carrier tube; a stiffening rod dimensioned to beslidably received within said single lumen carrier tube and having asufficient length extending between a distance beyond the distal end ofthe single lumen carrier tube to be received within the interior of theelastically deformable implant member and another distance beyond aproximal end of said single lumen working cannula to facilitatecollapsing the elastically deformable implant member onto a distal endof said stiffening rod; and a push off tube to facilitate the removal ofthe elastically deformable implant member from said single lumen carriertube once filled with said known volume of filler material, said pushoff tube dimensioned to be slidably received within said single lumenworking cannula and for slidably receiving therein said single lumencarrier tube; said push off tube having arranged about its distal endthe protective sheath, said sheath extending beyond a distal end of theelastically deformable implant member during its placement within thenucleus cavity; said push off tube having disposed at about its proximalend a bayonet fitted collar dimensioned to be received within saidcannula collar to facilitate locking engagement between the single lumenworking cannula and the closed insertion assembly; and the proximal endmagnetic mount being coupled to a tube connector in fluid communicationwith said carrier tube to facilitate coupling said closed insertionsystem to said closed dispensing system without relative rotationalmotion therebetween for filling of the elastically deformable implantmember with said known volume of filler material without fluidevacuation from the closed implant system.
 14. An apparatus for use witha working cannula, said cannula being configured to be fixedly dockedpercutaneously to an in situ implant site, the apparatus comprising: aclosed dispensing assembly which includes a distal end magnetic mountfor removably coupling said closed dispensing assembly to a workingcannula and a proximal end magnetic mount for removably coupling saidclosed dispensing assembly to a closed suing assembly during an implantsite size determination procedure and for removably coupling said closeddispensing assembly to a closed insertion assembly in place and stead ofsaid closed sizing assembly during an implant placement and fillingprocedure; said closed sizing assembly is configured to be partiallyreceived within the working cannula for carrying at a distal end thereofan elastically deformable mock implant member to an in situ implant siteto facilitate determining, without fluid evacuation from a closedimplant system, a known volume of filler material to substantially filla prosthesis implant to be formed at the implant site; wherein theclosed insertion assembly is configured to be partially received withinsaid working cannula in place and stead of the closed sizing assemblyfor protectively carrying an elastically deformable implant member tothe in situ implant site to facilitate its filling with the known volumeof filler material; wherein the closed dispensing assembly is configuredto be partially received within the working cannula and removablycoupled to the closed insertion assembly to facilitate the filling ofthe elastically deformable implant member with the known volume offiller material without fluid evacuation from the closed implant system;wherein said distal end magnetic mount facilitates connecting anddisconnecting said dispensing assembly from said working cannula withoutrelative rotational motion therebetween to help reduce tissue trauma tothe patient; and wherein said proximal end magnetic mount facilitatesconnecting and disconnecting said dispensing assembly from said closedsizing assembly without relative rotational motion therebetween tofurther help reduce tissue trauma to the patient and to furtherfacilitate connecting and disconnecting said dispensing assembly fromsaid insertion assembly without relative rotational motion therebetweento still further help reduce tissue trauma to the patient.
 15. Aself-contained closed implant system for the formation of a prosthesisdevice percutaneously at an in situ implant site, comprising: a singlelumen working cannula, said single lumen working cannula configured tobe docked against an outer surface area of the in situ implant site forthe implanting of a prosthesis device percutaneously at an in situimplant site; a closed sizing assembly configured to be partiallyreceived within the single lumen working cannula, said closed sizingassembly for carrying at a distal end thereof an elastically deformablemock implant member to the in situ implant site to facilitatedetermining, without fluid evacuation from the closed implant system, aknown volume of filler material to substantially fill the volume of animplant receiving cavity; a closed insertion assembly configured to bepartially received within said single lumen working cannula in place andstead of said closed sizing assembly for protectively carrying anelastically deformable implant member to the in situ implant site tofacilitate its filling with said known volume of filler material; aclosed dispensing assembly configured to be partially received withinsaid single lumen working cannula and removably coupled to said closedinsertion assembly without relative rotational motion therebetween tofacilitate the filling of the elastically deformable implant member withsaid known volume of filler material without fluid evacuation from theclosed implant system; and wherein the closed dispensing assemblyincludes a distal end magnetic mount for removably coupling the closeddispensing assembly to the single lumen working cannula and a proximalend magnetic mount for removably coupling the closed dispensing assemblyto the closed sizing assembly to facilitate determining, without fluidevacuation from the closed implant system, the known volume of fillermaterial to substantially fill the volume of the implant receivingcavity and for removably coupling the dispensing assembly to the closedinsertion assembly in place and stead of the closed sizing assembly tofacilitate the filling of the elastically deformable implant member withthe known volume of filler material without fluid evacuation from theclosed implant system to help reduce tissue trauma to a patient byobviating relative rotational coupling motions.